## ELECTRICITY from 2017

FINISHED!! 29/11/17

Electricity 2017  Final word version of the final electricity unit for Lockerbie

The booklet is large as it contains lots of questions for you to practice, some practicals for you to complete and some notes. These are currently in for copying, but hopefully in the next few days you should get your own copy. Please return it to the faculty on 8th May!

The section numbers are linked to the compendium with all the things to cover in National 5 Physics.

They are large notes so that you ought to be able to work your way through whether you are in class or away at college etc.

Electricity 2017 19 word version

Here are some additional notes that might help as you go through the materials. Check out the post on using your calculators to measure resistance (I’ll add the link here when I’ve found the post!)

Traces

EE1 – Electricity LOCKERBIE The old electricity notes (based on a colleagues work- thank you and I’ll find out who you are), these will be superceded when the document above is completed.

AC_DC[1] This is a powerpoint presentation that someone passed to be in the days of SG. It covers AC and DC traces

resistor network Try this when you think you have got to grips with resistances in series and parallel.

Elect & elect D&G Prob Book no answers These are some great little questions by Mr Belford from Dumfries Academy, but some of the numbers are a little bit fictional!

Elect & elect D&G Prob Book no answers The above document as a pdf file.

Voltage (2)

Voltage Analogy

VOLTAGE DIVIDER FORMULAE The formula sheet for voltage dividers

VOLTAGE divider circuits (2)

VOLTAGE divider circuits2

POTENTIAL DIVIDERS2

POTENTIAL DIVIDERS

VOLTAGE divider Q  Practice those horrible voltage divider questions with this pdf version of the document below. The answers are given for you to check. VOLTAGE divider Q

Ring main   Based on the SG course notes and not really in the N5 course, but it might give a little background to why when calculating the fuse rating for an appliance you use 240V and not the 230 V as stated.

…… to be continued!

## Dynamics 2017

I am in the middle of updating the Dynamics and Space Unit to be in line with the course from 2017. These are the current notes, but as you can see there is still a lot of work to do to get them completed.

Dynamics 2017_15 word

These are examples to find acceleration and displacement from v-t graphs. v-t graph examples.

Currently I’ve worked out the displacements. I’ll add the accelerations when I’ve done them! v-t graph example answers

LO Dynamics (1st half) Here are the revision questions for the first part of the unit. Eventually I’ll get them all completed. Answers to follow a.s.a.p.

LO Q N5_2017_5 word

Here are the answers for the Dynamics Learning Outcome Questions. I haven’t finished, but I am getting through them. It is a lot harder than just writing them out as I’ve the equations to type in! Well that is my excuse

LO LO Dynamics ANSWERS pdf This is as far as I’ve got Monday 30/10 21:16

LO Dynamics ANSWERS word This is as far as I’ve got!

##### Homework

N5 D&S Problem Booklet

Dynam & Space D&G PS Book

parachutes pdf file of the power point

parachutes power point

Projectile questions pdf file of projectile questions

Projectile questions

mass and weight

mass and weight

work done calculations

Latent Heat questions

### Revision Questions

Use the pdf file, printed from a powerpoint presentation to practice work for the D&S topic. Some space has been left so that you can record your answers on the sheets. They are saved 6 slides to a page

Dynamics and Space Revision

### Revision Practice

Need help with motion graphs, practice with this link

https://tinycards.duolingo.com/decks/motion graphs

https://tinycards.duolingo.com/decks/equations

https://tinycards.duolingo.com/decks/more equations

### Resources from other schools

I would like to thank all the schools who have produced notes that are reproduced here. Know that I am really grateful. I have a half finished set of my own notes, but don’t think I can get them suitably done in time. Be assured that at least you’ll have some excellent higher notes next year, and after those scores I am expecting a big Higher class 2017-2018!

Dynamics and space part1

Dynamics and space part2

The above two booklets count as one!

N4 N5 Unit 1 Summary Notes[1]

N4 N5 Unit 1 Summary Notes[1] These are the same set of notes, one is in word, but for those that cannot read that the other is a pdf file, which you ought to be able to read.

D&S Summary Notes

The notes below would be combined into one booklet (the one at the end of this section)

N5 DS Mar 13 Dynamics Teacher notes

N5 DS Mar 13 Forces Pupil notes

N5 DS Mar 13 Forces Teacher notes

N5 DS Mar 13 Space Pupil notes

N5 DS Mar 13 Space Teacher notes

N5 DS Pupil material notes FINAL COPY 13th JUNE

N5 DS Pupil material notes FINAL COPY 13th JUNE

The booklet below is an Intermediate 2 booklet and contains some material for other topics and some material is missing. It might be a good idea to get yourself a copy of this, if possible, especially if you are not a great lover of the heat section!

I2_Mechanics&Heat

Here are some more notes produced for Intermediate 2. There are some good questions here, but it does not cover all of the topic we are about to complete.

3779 Int 2

I will add some cut-outs and single page resources as we go through the course. If you lose yours, you will have to print them off yourself or take a photo!

##### Other Resources

N5 D&S Problem Booklet

N5 DS Past Paper Booklet

REVISION OF BGE TRANSPORT MATERIALS

## Past Papers for National 5 Physics

N5 PapersYearMarking
Instructions
Exam
Reports
2018
Specimen
QP & MI
New
Model
Specimen
QP & MI
Assignment
Assessment
QP 20172017MI 2017Report 2017
QP 20162016MI 2016Report 2016
QP 20152015MI 2015Report 2015
QP 20142014MI 2014Report 2014
Specimen
QP & MI
ModelSpecimen
QP & MI
FIRSTMARK GUIDE

### SG Physics Papers

Here is my latest offering, which is still under construction, click on the link to take you to the store of SG Physics Past Papers with as many Marking Instructions as I could find.

SG Past Papers

### Intermediate 2 Physics Papers

Here are the Intermediate 2 Physics Papers. The table isn’t yet complete, but you might want to start looking over some questions. Many of these could pop up on National 5 papers.

Int 2 PapersYearMarking
Instructions
Exam
Reports
Int2 20152015MI 2015
Int2 20142014MI 2014
Int2 20132013MI 2013
Int2 20122012MI 2012
Int2 20112011MI 2011
Int2 20102010MI 2010
Int2 20092009MI 2009
Int2 20082008MI 2008
Int2 20072007MI 2007
2006MI 2006
2005MI 2005
2004MI 2004
2003MI 2003
2002MI 2002
2001MI 2001
2000MI 2000
FIRSTMARK GUIDE

# Welcome to National 5 Physics.

We hope you enjoy the experiences you will have learning Physics over the next year. We want you to have a clear idea of what you will need to complete during the course so we have produced this information.

# SURVIVING THE COURSE.

## 1. The structure of the Course.

It may not have crossed your mind but the first thing to understand if you are to achieve the best that you can in Physics at National 5 is to have a clear understanding of how the course is run. The course is made up of several parts. These can be divided up in several ways.

There are six units and the Assignment (which changed for the session 2017-18):

1. Waves
3. Dynamics
4. Space
5. Electricity
6. Properties of Matter
7. Assignment (20% of the course covered in class but marked externally)

Dynamics – the topics covered are: vectors and scalars; velocity–time graphs; acceleration; Newton’s laws; energy; projectile motion.

Space – the topics covered are: space exploration; cosmology.

Electricity-the topics covered are: electrical charge carriers; potential difference (voltage); Ohm’s law; practical electrical and electronic circuits; electrical power.

Properties of matter –the topics covered are: specific heat capacity; specific latent heat; gas laws and the kinetic model.

Waves – the topics covered are: wave parameters and behaviours; electromagnetic spectrum; refraction of light.

Eventually, for each unit, you will have a set of Learning Outcome Questions to complete, these are what you have to know for the exam, and also give you a good grounding in Physics should you go on to study the subject further (which we hope you will). These questions will be uploaded to the website. When you have been given the chance to complete these, they have been corrected by your teacher, you will complete an end of section test. The tests will comprise knowledge, understanding, analysis, problem solving, skills etc.

The Assignment and Exam will test:

• knowledge and understanding of physics by making accurate statements
• knowledge and understanding of physics by describing information and providing explanations and integrating knowledge
• applying physics knowledge to new situations, interpreting information and solving problems
• planning or designing experiments to test given hypotheses or to illustrate particular effects, including safety measures
• carrying out experimental procedures safely
• selecting information from a variety of sources
• presenting information appropriately in a variety of forms
• processing information (using calculations and units, where appropriate)
• making predictions based on evidence/information
• drawing valid conclusions and giving explanations supported by evidence/justification
• evaluating experimental procedures
• suggesting improvements to experiments/practical investigations
• communicating findings/information

In summary the course will be completed in the following order:

• Maths and Intro
• Waves
• Dynamics
• Assignment
• Properties of Matter
• Space
• The exam

## 2. The Need to Know Booklet and organising you work.

Currently, all the information you need to pass the exam is highlighted in the Outcome Booklet (which really does need to be given a better name). You should be scrutinising this lesson by lesson to check your progress through the course and to ensure you understand what you are required to know and learn. Eventually, we hope to produce a set of Learning Outcome Questions, the answers to which will provide you with a perfect set of revision notes. The difficulty is that the course is changing more rapidly than we can keep up with the production of the questions.  You must make sure that these are answered clearly and concisely in your Notes section. Either copy out each question or print the questions and stick these in your notes. Then your friends and parents can use this to test you at the end of a section and close to exams. Alternatively, you can make these into flash cards, that can be slipped onto a keyring which you can have with you more readily!

Another hint is to make your work as colourful as possible. It must also be neat. This is going to form your most important work so take care of it. If it is bright, colourful, well presented and laid out it will be easy to revise from. If your notes section is scruffy and disorganised you will find it more difficult to revise, and when you do sit down to revise you will find alternative things to do as the process is so hard and unpleasant. Hand in your notes work regularly for checking.

At the back of the notes jotter keep a list of all of your quantities etc. in a table like the one below. Please note that the third column needs to be the widest, then followed by column one; column two and four can be very narrow.

QuantitySymbolUnitUnit Symbol

Your formulae should also be in the notes section. Keep the list up to date! Each time that you learn a new formula put this in your notes. Make sure you include units, symbols and the meaning of each letter. Check that you can rearrange the formula to find any missing quantity.

The work that you do in class should usually be written in your class work jotter. Date all work and record a title for each activity. Sometimes notes will go straight into your notes jotter, so you must have this with you every lesson.

bullseye

### 3. Follow the Rules & Routines & Bring Equipment

The five rules of the Physics Department are for pupils follow to ensure a pleasant and safe environment.

2. Raise your hand, and wait for permission before speaking.
3. Allow people to get on with their work.
5. No put downs. (or only say positive things about people).

Remember Science is about trial and error and looking for ways to fix mistakes, what a better example for life!

### ROUTINES

In addition to the core rules the following routines are expected of pupils during their time in this department. Pupils should:

1. Enter the room quietly, calmly and on time;
2. Come prepared for the work with jotters and pen or pencil etc.;
3. Complete all homework and hand it in on time;
4. Not deface jotters, desks folders, etc.;
5. Pay attention;
6. At the end of a lesson, when told to do so, pack away quietly, place stools under the desk and leave in an orderly manner.

## 3.  Homework and Review

You will be expected to complete all the homework set and hand it in on time. We will contact parents/carers if we think you are not completing this vital part of the course. We do not issue homework because we want you to spend all your life working, but because it gives you the opportunity to consolidate the work completed in class. It has been proved that students who complete homework do better in their exams.

## 4. The Timeline

You will be issued with a timeline. This may be on a monthly, weekly or termly basis. This will show you what homework you will have to do, where on the course you are and when assessment dates are likely to be. We may have to update this through the year but it should be used to plan study and work. Don’t waste it, use it!

If you do not understand any aspect of the course or work and you have read through the material at home then ask. Both members of the Department (Mrs Physics and Ms Horn) are willing to help you with your work.

## 6. Equipment

This is a list of the equipment you need to bring to Physics

• Pen
• Pencil
• Ruler (30 cm)
• Eraser
• Protractor or angle measurer.
• Scientific calculator, nothing fancy but it must be capable of doing scientific functions. Most pupils find it easier to use a Casio DAL, S-VPAM calculator, particularly the Casio FX83 or Casio FX85. With these calculators you enter the numbers into the calculator in the manner in which they are written. There is a post in the maths section giving you some example of how to work your calculator and I’ll add a few more hints later in the year.

#### Pupils will be issued with

• A classwork jotter for practice and results
• A notes jotter
• A homework / profile jotter
• An A5 Content booklet containing the Content Requirements, Relationships’ Sheet, Periodic Table and a few maths hints. This should be brought to every lesson and used every night to check content coverage and for revision and review. This can be kept at the end of the course as it will be covered in student writing.
• Eventually students will receive Activity booklets with all their content and questions, these are currently being produced. These should be returned at the end of the course.

## 7. Take Responsibility for your Learning

Sometimes there may be a distraction in the classroom that is out of my control. Make sure that you use your time wisely if there is a distraction. Check and complete one or more of the activities listed below.

• Finish off the work that has been set.
• Complete Learning Outcome Questions/ Summary of content statements.
• Check off the content covered in the Vital Booklet (good name needed)
• Write out a summary of what you have been doing.
• Read through the work that we have been covering.
• Read through the next section of work to prepare.
• Produce a revision test for the class.

Your work is in your hands. This is time that can be used or abused. If you abuse your time now you will have to use your free time later. SPEND YOUR TIME WELL.

## 8. Layout for Tackling Mathematical Problems

Always set out maths problems using the structure given below. It may seem to take longer but it will save time in the long run as it makes the question clearer.

#### USE IESSUU

1. Information– Summarise the question by writing down what you know from the information given. Use the letter that goes with the quantity and this will help you be able to work out the correct formula
2. Equation – write down the equation as it occurs in the data sheet. Do not attempt to rearrange it before substituting.
3. Substitution – put the numbers into the equation as they appear in the formula
4. Solution – work out the answer. You are ALWAYS allowed to use a calculator
5. Units– you will need to use the correct units so will need to learn these. No or wrong units no mark for the answer
6. Underline – underline with 2 lines the answer to make it clear what is your final answer.

In short:

1. (Information)- Summarise the question.
2. Change any units that are not standard.
3. (Equation) -Write out the formula.
4. (Substitution) -Put the numbers in.
5. Use the magic triangle to rearrange the formula, only if you must!
6. (Solution)- Work out the answer.
7. Write out the answer, but not to too many sig fig.

http://www.sqa.org.uk/sqa/files_ccc/Physicsgeneralmarkingprinciples.pdf

## 9. Revising The Syllabus

REVISING- Here are some really important ideas to help you with your revision (which shouldn’t just take place the night before a test but should be an ongoing process).

Find out:

• Make a Revision Calendar (I’ve made one for you Click Here! The instructions can be found in the Revision section)
• Stick a large calendar next to where you study.
• Mark in the dates and times of Exams (whether prelims or final exams). A counter has been added to the N5 Home Page.
• Shade in the dates and times of other commitments.
• Make a list of topics to cover for each subject.
• Calculate how many hours you have available and how much time you will allocate to each subject.
• Decide on the order in which to tackle your subjects. Don’t tackle the easy subjects first as you’ll never get on to the harder ones! It is best to start revising the hard subjects and topics as these will take you more time to learn
• Leave one or two revision slots free each week for extra revision or difficult topics.
• BE SURE TO LEAVE YOURSELF SOME TIME FOR REST AND FUN ACTIVITIES including being healthy.
##### This can be useful but:
• Discipline is needed
• Decide before you meet on the topic that you’ll cover e.g. prepare revision cards or answer past paper questions.
• Teach each other a topic
• Take an ACTIVE APPROACH to your Revision
• Talking with others about what to revise can lessen the anxiety.
• Before starting a Session decide HOW  and WHAT to revise

A STEP BY STEP REVISION STRATEGY

• FIND A FOCUS
• MAKE REVISION CARDS
• TEST YOURSELF
• LEARN IT!
• TEST YOURSELF
• CHECK IT!

## 10. Relax

Believe it or not we also expect you to make sure that you do have time to relax. Relaxation should be in proportion. Too much and you won=t finish the work, too little and you will not function properly. Balance is important. Make sure that your relaxation includes plenty of exercise and fresh air. Don’t just vegetate in front of something electrical.

Now that you have your survival guide to the course may I wish you all the best and hope that you go on to perform Physics to the best of your ability, whatever that standard is!

Remember we are a TEAM! It is not YOU ALONE! It will be most effective if YOU, ME and PEOPLE FROM HOME can all work together to support you through the next nine months. We each have a role to play. I need to explain what we need to do in the best way I can, and ensure you know the course content. Your role is to listen well in class, learn what you are taught, ask if you have not understood what you’ve been taught and review and revise little and often. Tell me if you are finding the work hard so that I can give you additional support. People at home are there to support and encourage you in your work and if possible test you on your learning, (provided you’ve laid it out as well as possible).

### After a Test

It is important that you review your performance after a test. One way to do that is through a Thinking about Revising Sheet.

Thinking about revising this is the word version

Here is the link to the SQA N5 Physics website

## Monthly Progress Chart

Each month, (handing in your jotter on the first Physics period of the month), give an update on how you feel you’re getting on in Physics, reassess your targets and check through your progress. You ought to be able to tackle new past paper questions every month. For the first Progress Chart answer the questions contained in the profile below and write out the expectations and sign these.

#### PUPIL PROFILE

Name:

Date of Birth:

Register Class:

Registration Room:

Register Teacher:

Pupil Support Teacher:

House:

Maths Class:

Maths Teacher:

Approx. level Maths: N3, N4, N5

English Class:

English Teacher:

Approx. level English: N3, N4, N5.

Other subjects taken:

1

2

3

4

5

6

Tell us a little bit about yourself so that we can make the work as relevant to you as possible. Include things like

•         where you live,
•         the other people in your family,
•         what you most like doing,
•         how you spend your time outside school.

You could also include what kind of career you would like to have, what your goals are in life, and why you chose to take Physics.

##### Target Setting

During my time in Physics I want to achieve the following targets.

### Expectations

will always do my best in N5 Physics

I will work hard in class, and follow the classroom code.

I will look over the work I have done each evening, and I complete each piece of homework and hand it in on time.

If I am absent I will catch up on the missed work and homework and ask if I am stuck.

I will ask my teacher for help when I am having difficulties, and will not give up.

I will show my homework to my parents when completed.

signed (you)

(and your parent/guardian to show that they have seen this)

Best Wishes for a lovely journey through N5 Physics

## Waves Resources

Here are a list of current wave resources. I will add more as I go through them. Thanks to other schools if you have kindly supplied material. I really appreciate it as do my students.

waves-summary-notes-gairloch1 Some of these notes are for National 4, use with the content statements so you don’t spend too long learning the National 4 work.

vflambda-vdt This starts with a practical model that you can complete in class using the Virtual Physics/ Flash Learning. It then shows how v=fλ is equivalent to v=d/t. Finally some questions will let you practise what you know.

Waves

I2_Waves&Optics

Here are the WAVES outcome answers. Not quite finished, but I bet I’ve done a better job than most of you (M&M excluded)

## Definitions for Space

These are some very basic definitions for the Space Topic

 Universe: Sum total of everything that exists. Galaxy: A basic building block of the universe that includes stars, star clusters, clouds of gas, dust and interstellar molecules. Solar System: Is one or more suns surrounded by orbiting planets. Our solar system is composed of the sun, 9 known planets and at least 44 moons, thousands of “minor planets” (asteroids) meteors and perhaps billions of comets. Sun: Dominant member of a solar system accounts 99% of the mass of the solar system. The sun is a giant star it produces heat and light. A big ball of plasma Star: Principle components of galaxies. Living stars emit radiation across the electromagnetic spectrum.  Peak depends on the heat of the surface. Planet: A relatively large body rotating in an elliptical orbit around a sun. Moon: A natural satellite of a planet i.e. rotates around a planet. Moons do not produce their own light. Mass: Mass is a measure of the amount of matter in an object. It is measured in kilograms. Wherever you go your mass stays the same. Weight: Weight is the force of gravity acting on an object pulling it towards the centre of the Earth or any other large mass. Weight is a force and so is measured in Newtons. The weight of an object varies depending on where you are (which planet etc and how far you are from it’s surface, the further away from the surface the smaller is your weight).. gravitational field strength : gravitational field strength, g, is the weight per unit mass. It is measured in Newtons per kilogram. It is the force of gravity or pull on each kilogram of mass. Inertia: Inertia is the property of an object which makes it hard to get an object to move, or to stop a moving object. Inertia varies with mass, so the bigger your mass the bigger your inertia.. Acceleration due to gravity: All objects will acceleration due to gravity. On the Earth, close to the surface objects accelerate at 9.8 ms-2 . Light year: The distance light travels in a year equivalent to 9.46 .
##### Light

Light does not travel at an infinite speed. It takes time to travel. It is so fast that we do not usually notice, although out in space the distances involved are so big that light takes a reasonable amount of time to reach us.

Light travels at: 3 × 108 ms -1

Given that it takes 8 minutes for light to get from the sun, how far is it away is it from the Earth?

8 × 60  = number of seconds in minutes  = 480s

Each second light travels 3 × 108m

d= v t

d= 3 × 108   × 480  = 1.44 ×1011m

How far does light travel in one year?

1 year  = 365days

365days  × 24 = 8760 hours

8760 ×60 × 60  = 31536000s in one year

Distance travelled in 1 year, d = v t

d = 3 × 108 × 31536000     = 9.46 × 1015 m in one year = one light year

The light year (ly) is the distance light travels in one year.

Light travels at 3 × 108 ms-1

 Source Time taken for light to reach us Distance (m) Working Moon 1.2 s 3.6 × 108 1.2 × 3 × 108 Sun 8 min 1.44 × 1011 480 × 3 × 108 Next nearest Star 4.3 y 4.07 × 1016 4.3 × 9.46 × 1015 Other side of galaxy 100 000 y 9.46 × 1020 100 000 × 9.46 × 1015 Andromeda galaxy 2 200 000 yr 2.08 × 1022 2 200 000 × 9.46 × 1015
##### Continuous Spectra

Many light sources produce a continuous spectrum containing all the wavelengths of visible light, e.g. an ordinary light bulb.

##### Line Spectra.

Some light sources emit only some wavelengths. They produce a line spectrum. Each line corresponds to a particular wavelength.

Each chemical element has its own line spectrum pattern(so it is like a finger print!)

Line spectra can be varied using a spectro-scope in the classroom.

Line spectra are used to tell us about the chemical composition of the stars.

# Time for activity to (decrease by) half or  time for half the nuclei to decay

(It is measured in units of time, e.g seconds, minutes, days, years, millions of years!)

##### Note the SQA do NOT accept: Time for radiation/radioactivity/ count rate to half

From the Yellow Chemcord Book- this is how to answer the questions HALF LIFE QUESTIONS

Chemcord have kindly giving permission to upload these questions here. If you thought they were useful you can buy the National 5 Revision books soon:

Chemcord Sample N5

half life Questions A print out for those who would like a copy of the National 5 Chemcord revision questions on half life. Here are the questions written out: HALF LIFE QUESTIONS

1. What is meant by the half life of a radioactive substance?
2. The activity of a source drops from 1000 kBq to 125 kBq in 9 days. Calculate the half life of the source.
3. The activity of a source drops from 4800 kBq to 150 kBq in 10 days. Calculate the half life of the source.
4. The activity of a source drops from 720 MBq to 45 MBq in 20 years. Calculate the half life of the source.
5. The activity of a source drops from 4096 kBq to 1 kBq in 2 days. Calculate the half life of the source.
6. The activity of a source drops from 448 kBq to 3.5 kBq in 17.5 years. Calculate the half life of the source.
7. A source has an activity of 1800 kBq and a half life of 2 days. What is its activity 10 days later?
8. A source has an activity of 576 MBq and a half life of 30 years. What is its activity 180 years later?
9. A source has an activity of 2400 kBq and a half life of 8 s. What is its activity 32 s later?
10. A source has an activity of 3200 kBq and a half life of 5.3 days. What is its activity 37.1 days later?
11. A source has an activity of 800 kBq after being stored for 4 days. If the half life is 1 day, what was its initial activity?
12. A source has an activity of 1800 kBq after being stored for 72 s. If the half life is 24 s, what was its initial activity?
13. A source has an activity of 40 kBq after being stored for 10 years. If the half life is 2 years, what was its initial activity?
14. A source has an activity of 30 kBq after being stored for 2 days. If the half life is 8 h, what was its initial activity?
15. A source has an activity of 40 MBq and a half life of 15 s. How long will it take for its activity to drop to 625 kBq?
16. A source has an activity of 25 MBq and a half life of 8 days. Approximately how long will it take for its activity to drop to below 1MBq?
17. A source has an activity of 320 MBq and a half life of 1000 years. Approximately how long will it take for its activity to drop to 500 kBq?
18. A background count rate of 20 counts per minute is measured in the absence’ of a source. When the source is present the count is 140 counts per minute initially, dropping to 35 counts per minute after 15 days. What is the half life to of the source?
19. If the background count is 28 counts per minute and the count with a source drops from 932 to 141 counts per minute in 24 h, what is the half life of the source?
20. If the background count rate is 24 counts per minute and the count rate with a source present drops from 4120 to 25 counts per minute in 2 days, what is the half life of the source?
21. In an experiment with a radioactive source, the count rate corrected for background radiation was measured and the following results obtained.
 Time in minutes Corrected Count Rate in c.p.m. 0 1 2 3 4 5 100 58 32 18 10 5.6

a) Plot a graph to show these results.

b) Estimate the half life of the source from these results.

22. In an experiment with a source, carried out in an area where there is a high background radiation, the following results were obtained.

 Time (s) Count Rate  (c.p.m.) 0 30 60 90 120 150 180 210 240 270 300 88 72 60 52 44 39 36 34 32 29 30

a) Plot a graph to show these results.

b) Estimate the background count rate.

c) Estimate the half life of the source from these results.

1. time taken for the activity to decrease by half
2. 3 days
3. 2 days
4. 5 years
5. 4h
6. 2.5 years
7. 56.25kBq
8. 9 MBq
9. l50 kBq
10. 25 kBq
11. 12.8 MBq
12. 14.4 MBq
13. 1.28 MBq
14. 1920 kBq
15. 90s
16. 32 to 40days
17. 9500 years
18. 5 days
19. 8 h
20. 73.   4h

For Questions 2-6 (to find t ½ when Ao and A known)

Step

1. Summarise
2. Starting with the original activity keep halving until you reach the final activity
3. COUNT THE ARROWS. This is the NUMBER of half lives.
4. Use the formula    t½= time÷No. of t ½
5. Don’t forget to write out the time.

For Questions 7-10 (to find the final activity when t and t ½  are known)  Step

1. Summarise
2. Use the formula to find the number of half lives (this will be the number of arrows) No. of t ½ = time÷ t½
3. Starting with the original activity keep halving until you reach the final activity
4. COUNT THE ARROWS. This is the NUMBER of half lives.
5. Don’t forget to write out the units for final activity.

For Questions 11-14 (to find Ao when A, t ½ and time are known)

Steps

1. Summarise
2. Use the formula to find the number of half lives (this will be the number of arrows)   No. of t ½ = time÷ t½
3. DOUBLE the final activity for the number of t ½ eg If you have 4 half lives double the final activity 4 times. NB DO NOT MULTIPLY BY 4
• The alternative is to MULTIPLY the final activity by 2n (2 to the power n where n is the number of half lives)
• The number at the end of the arrows is your original activity, don’t forget to add the units.

For Questions 15-17

Step

1. Summarise
2. Starting with the original activity keep halving until you reach the final activity
3. Count the Arrows
4. Use the formula     time = t½ × No. of t ½

### Experiment to Measure Half Life

The activity of a radioactive source decreases time. However the rate of decrease slows with time. Because of this, and because the decay of individual atoms is random and unpredictable, theoretically a radioactive source will never completely lose all of its activity. The time taken for half of the atoms in a radioactive sample to decay is a constant for that source called the half-life of the source. So the half-life of a radioactive source is the time period during which the activity of the source falls to half of its original value. The half-life of some sources is as low as a fraction of a second; for others it is many thousands of years.

Finding the half-life of a radioactive source

Apparatus: Geiger-Muller tube, Scaler counter or ratemeter, Source (eg.sealed protactinium-234 radioactive source and drip tray).

Instructions:

• Use the Geiger-Muller tube and scaler counter to measure the back­ground count rate.
• Record this value.
• Set up the apparatus shown in the diagram.
• Measure and record values of count rate and time interval for a suit­able time period.
• Correct all your measurements for background by taking the background count off all other measured count rates..
• Plot a graph of COUNT RATE or ACTIVITY against TIME.
• Find the half life from the graph

Half life and safety

To measure the half-life of a radioactive source, the level of the background radiation is first measured. Then the count rate with the radioactive source present is measured over a suitable period of time using a suitable detector such as a Geiger-Muller tube connected to a scaler. A graph of the count rate (with the source present), corrected for background radiation, is plotted.A suitable count rate value is chosen, say 80 counts per minute, and the time at which the source had this count rate, t1, is marked as above. In a similar way the time t2 at which the count rate is half the previous value, 40 counts per minute, is found. The half-life of the source is the time period t2 -t1. Any starting value can be chosen, the time period for the count rate to halve in value will always be the same.

EXAMPLE

In six years, the activity of a radioactive isotope drops from 200 kBq to 25kBq. Calculate the half-life of the isotope.

SOLUTION: original activity = 200 kBq

Activity after 1 half-life = ½ ×200 kBq = 100 kBq

Activity after 2 half-lives = ½ × 100 kBq = 50 kBq

Activity after 3 half-lives = ½ × 50kBq = 25 kBq

So 6 years represents 3 half-lives, thus one half-life is 2 years.

There are several safety precautions that must be taken when handling radioactive substances.

• Always handle radioactive substances with forceps. Do not use bare hands.
• Never point radioactive substances at anyone.
• Wash hands thoroughly after using radioactive substances especially after using open sources or radioactive rock samples.
• Unauthorised people must not be allowed to handle radioactive substances. In particular, in the United Kingdom, no one under 16 years of age may handle radioactive substances.

In addition there are several safety precautions relating to the storage and monitoring of radioactive substances.

• As soon as source has been used, return it to its safe storage container, to avoid unnecessary contamination.
• Keep a record of the use of all radioactive sources.

The equivalent dose received by people can be reduced by three methods:

• shielding;
• limiting the time of exposure;
• increasing the distance from the source.

Stay safe and keep under your annual dose of 2.2 mSv!

## Half life Results- Protactinium-234 and Indium-116

Here are the results from the Protactinium Generator Experiment. Your task is to correct for background (take the background count per second away from the count rate) and then plot a graph of count rate (cps) against time (s). Remember the count rate was taken every 10 s but shows the value of the count rate (for one second)

Background count rate (c.p.m.) 48.0,   46.0,   42.0

Average background count rate (c.p.m.)    45.3

Average background per second (c.p.s.)    work it out!

TimeCount rate
(s)(cps)
080.3
1073.9
2067.3
3060.5
4055.2
5049.6
6045.7
7041.5
8037.4
9034.1
10031.3
11028.5
12025.9
13023.9
14021.7
15019.4
16017.6
17016
18014.9
19013.4
20012.3
21011.2
22010.2
2309.2
2408.4
2507.5
2606.9
2706.4
2805.7
2905.3
3004.7

##### Indium 116 Half Life

Here are the results for the Indium-116 half life experiment. Warning, do not plot a graph in 15 minute intervals or you will have more difficulty finding the half life. Make the scale ten minute intervals.

You can track the experiment yourself through the link below

Indium-116 files

Background count = 31 c.p.m.

Time Time from startCount rate
(hours)(mins)(c.p.s.)
9:000675
9:1515570
9:3030452
9:4545375
10:0060328
10:1575275
10:3090219
10:45105181
11:00120164
11:15135149
11:30150126
11:45165106
12:0018090

Here are three more examples for you to practice producing a half life graph and for finding the half life of Protactinium

##### Example 1:

Background Count (cps):    5,   5,   3,  5,   4,   5,   5.

Time (s)Count in 10s
0308
10279
20240
30217
40197
50182
60165
70158
80145
90129
100116
110109
12098
13089
14080
15075
16066
17060
18055
19050
20046
21043
22035
##### Example 2:

Background Count (cps):     4,       3,      5.

Time (s)Count in 10s
0841
10752
20693
30622
40593
50544
60481
70443
80392
90364
100341
110301
120272
130251
140243
150211
160204
170183
180172
##### Example 3:
time
(s)
Count
in 10s
corrected
count
in 10s
Corrected
Count
Rate
(cps)
Background
count
(cp10s)
0
5105100.510.055
209590.59.055
358176.57.653
509085.58.555
658681.58.154.5
807368.56.85
957671.57.15
1107974.57.45
1255348.54.85
1405348.54.85
1555853.55.35
1706156.55.65
1856055.55.55
2004338.53.85
2156055.55.55
2304843.54.35
2454540.54.05
2604439.53.95
2754237.53.75
2904742.54.25
3052823.52.35
3203126.52.65
3353631.53.15
3503227.52.75
3652419.51.95

You should now have had plenty of practice at finding the half life graphically, nothing should phase you now.

## Waves Definitions

Here are some definitions to learn for the waves topic. Remember you must be able to spell:

## REFLECT, DIFFRACT and REFRACT

 Term Definition Amplitude (A) the distance from the middle of the wave to the top (or the bottom) measured in metres. Maximum displacement from the mean position! amplitude, (A) maximum disturbance of the particles in a wave. (or distance from middle to top of wave) (m) Angle of incidence the angle between an incident ray and the normal (a line perpendicular to the reflecting surface at the point of incidence) (°) Angle of reflection the angle between a reflected ray and the normal (°) Angle of refraction the angle between the light ray in the more optically dense material and the normal. (°) Critical angle The critical angle is the angle of incidence above which total internal reflection occurs. (°) Diffraction occurs when wave meet a barrier, the waves bend around an obstacle. Long waves diffract more thank short waves. Energy and waves Waves transmit energy. The greater the amplitude the more energy is transferred. Frequency, (f) the number of waves per second. Frequency is measured in hertz (Hz). Frequency, (f) number of waves produced or passing a point per second. (Hertz or Hz) Law of reflection The angle of incidence = the angle of reflection Longitudinal wave In a longitudinal wave the particles move along the line of the direction of travel of energy. Normal a line at 90° to the surface at the point of incidence, (from which all angles are measured.) Period. (T) Time for one wave to pass a point or time for one wave to be produced. (s) Principle of reversibility of light The principle of reversibility of light states that a ray of light which travels along any particular path from some point A to another point B travels by the same path when going from B to A. Reflection when a wave “bounces off” a surface we say it is reflected. (Particles can also reflect) Refraction when light waves travel from one material to another the waves slow down and there is a reduction in wavelength in the optical thicker material. Unless the waves enter along the normal there is also a change of direction. Speed, (v) rate of covering a distance. Number of metres travelled per second. (ms-1) The speed of the waves is represented by the formula Total Internal Reflection When a wave hits a boundary at an angle larger than the critial angle the wave is entirely reflected if the material on the other side of the boundary is less optically dense. Transverse wave In a transverse wave the particles move at 90 degrees to the direction of the flow of energy. Wave a way of transferring energy. Wave speed the speed at which the wave travels Wavelength the distance between the same point on successive waves. Wavelength, (λ) the distance between two successive points on a wave. (metre or m) Wavelength, (λ) The wavelength of a wave is the horizontal distance between two adjacent troughs or crests or any two corresponding points on the wave

## The Gas Laws

The pressure, volume and temperature of a gas all affect one another. This would make the results of an experiment to investigate changes in all three at once complicated to understand. This problem is overcome by making one of them stay constant, whilst the relationship between the other two is investigated.

# Boyle’s Law- Volume and Pressure

This Law is about the variation of (a fixed mass of gas) volume with the pressure of a gas at steady temperature. The apparatus shown in the diagrams below may be used to find how the volume of a fixed mass of gas varies with pressure at a constant room temperature.

A syringe can be compressed to increase the pressure which is measured using a pressure sensor. The fixed mass of gas, usually air is trapped in the syringe, and its volume read from the scale.

Alternatively a foot or bicycle pupil is used to increase the pressure which is measured on the Bourdon Gauge. The fixed mass of air is trapped in the capillary tube by a bead of mercury, and its volume measured on the scale.

How Pressure is related to volume for a constant mass and temperature of gas.

Pressure (kPa)100111125143167250
volume of air column(cm 3 )504540353020
Use the results to show a relationship

It is found that when the pressure in increased the volume of the gas decreased so that:

pressure × volume = constant

p × V = k

### Kinetic theory of Boyle’s law

The pressure of a gas is caused by the molecules hitting the walls of the container. Reducing the volume results in a shorter distance between the walls and so the number of molecules hitting the walls increases- resulting in increased pressure.

# The Pressure Law (Gay Lussac Law)

This law looks at the variation of pressure with temperature at constant volume. The apparatus shown below may be used to find how a fixed mass of gas, at constant volume varies with temperature.

The air is contained in a round bottom flask, which has a constant volume, and the pressure is measured using the pressure sensor attached to the flask by a short tube. It is important to have a short tube so that the temperature in the whole system is equal at any point. The round bottom flask is placed in a water bath which is used to vary the temperature of the water, and hence the air in the flask. Recent results have shown that the thermometer is best placed in the water bath as this gives more accurate results for the temperature of the air in the flask. Placing the thermometer in the flask usually results in a time delay in measuring the temperature of the air inside the flask. The flask should be fully immersed in the water, to ensure all the air in the flask is at the same temperature The temperature must be recorded as Absolute Temperature (in Kelvin) to find a relationship.

The pressure increases proportionally with the absolute temperature (i.e if you double the absolute temperature you will double the pressure provided the mass and volume remain constant). This can be expressed as:

### Kinetic theory of Pressure law

If the absolute temperature of a gas increases, the speed of the molecules increases. The force and frequency of the impacts on the walls of the container increases, as this is the cause of pressure,then pressure increases.

How Temperature is related to Pressure for a constant mass and volume of gas.

Temperature ( o C)0205080100
Pressure (kPa)93100110120127
Use this to show a relationship!

# Charles’ Law

This is about the variation of volume with temperature at constant pressure. The apparatus shown is used to find how the volume of air varies with temperature provided the pressure remains constant.

The pressure remains constant, since it is equal to the atmospheric pressure plus the small additional pressure due to the weight of the mercury bead on to of the trapped air. This is because the capillary tube is open at one end. The volume of air is measured on the scale and the water bath is used to vary the temperature. The absolute temperature must be used to find a relationship between pressure and volume.

It is found that the volume of the gas increases proportionally with the absolute temperature provided the pressure and mass remain constant. This can be expressed as:

###### Charles’ Law states that: For a fixed mass of gas at constant pressure the volumee is proportional to the absolute temperature. i.e. the volume divided by the temperature stays constant, provided the pressuree does not change.

Kinetic theory of Charles’ law

The pressure of a gas is caused by the molecules hitting the walls of the container. If the absolute temperature of the gas increases the speed of the molecules increases. This would result in more forceful and frequent collisions on the walls. However, to maintain the pressure then there must be no increase in the frequency and magnitude of the collisions, so the volume must increase.

How Temperature is related to volume for a constant mass and pressure of gas.

Temperature ( o C)020406080100
Length of air Column(cm)2021.522.924.425.927.3
Proportional to volume
Use these figures to show a relationship!

# The General Gas Law

The three separate gas laws can be summarised by one equation, known as the General Gas Equation:

This is often written as:

Where p1, V1 and T1 refer to one set of conditions of pressure volume and temperature, and p2, V2 and T2 to another set of conditions for the same mass of the same gas.

An individual gas law can be found from this equation by covering up the variable which is kept constant (or cancelling out the variable as it remains constant).

gas law results docx

gas law result pdf

Complete the three graphs above and for two of them try to work out the equation for the straight line, i.e. what is y = mx + c

# Pascal

The unit of pressure is the Pascal. I Pa is 1 Nm-2. You must remember you will not measure zero pressure as we have an atmosphere. I atmosphere is the pressure exerted due to our atmosphere and is approximately equal to 1 x105 Pa. This is equivalent to a weight of 105 N acting on a square of area 1m2. At ground level this is approximately the mass of 104 kg on a square metre which equates to about 10 Fiat 500 in 1m2.

# Questions

1. A mass of gas at a pressure of 20kPa has a volume of 3m3. What will be the volume if the pressured is doubled but the temperature remains constant?
2. The volume of mass of a gas is reduced from 5m3 to 2m3. If the pressure was initially 40 Pa, what will be the new pressure if the temperature remains constant?
3. The pressure of a fixed volume of gas at 300 K is increased from 5 Pa to 10 Pa, what will the new temperature be?
4. If pressure of a fixed volume of gas at 200 K is 50 Pa. What would be the pressure if the temperature is increased to 300 K?
5. The temperature of 6 m3 of gas is increased from 300 K to 400 K. What will be the new volume of the gas if the pressure remains constant?
6. The volume of a gas is increased from 10 m3 to 20 m3 at constant pressure. Calculate the new temperature if the initial temperature was 300 K.
7. A mass of gas has a volume of 5 m3, a pressure of 20 Pa and a temperature of 300 K. What will be the new pressure if the volume is changed to 4m3 and the temperature to 400 K?

## Voltage

Many teachers think that voltage is too difficult a concept for S1 students to understand. By the time students get to AH we expect them to be fully knowledgeable about voltage, but we don’t clearly explain it to them as we go along. I am as guilty as the next person of doing this so… . My new mission is to teach voltage as best and as fully as I can to S1 and build on the concept each year so that by AH they will feel confident about this work.

Having met Gill Arbuthnott at the Edinburgh International Book Festival (see post in Blog) I was really impressed with the way she tries to explain difficult concepts early on. She has given me permission to reproduce her page 16 on The Volt here.

The Volt

This was named after Alessandro Volta It is a unit of measurement in electricity. It tells us how much energy an electric charge has. You sometimes hear people saying things like, “The number of volts running through the circuit is…”. This doesn’t actually make sense! It’s like saying, “The height running through the mountain is 1000 metres.” Heights don’t run, and neither do volts. There is no Usain Volt!

What is a volt?

So what is a volt? Imagine you are in a building with stairs and a lift. You carry a tennis ball up one floor in the lift, and let it roll back to ground level down the stairs. A battery is like the lift – it’s a way of giving energy to something. In the building this is the ball – in electrical terms it’s an electron.

The ball rolling down the stairs is losing energy. In our circuit the equivalent is the electrons losing their energy to power a bulb. The voltage is equivalent to the height you take the ball up in the lift – more height is equivalent to greater voltage. And the distance the ball goes up in the lift must be the same as the distance it comes down by the stairs.

There are plenty of pictures in the book, but I didn’t think it was as easy to reproduce them. The book is full of more really interesting stuff, and even material about coins that Mr Chemistry opposite Mrs Physics didn’t know about (but then he’s far too young!)

http://www.bloomsbury.com/uk/a-beginners-guide-to-electricity-and-magnetism-9781472915740/

Definition: Potential difference is the amount of work done to move an electric charge from one point to another.

or

Definition: The definition of voltage is the electromotive force or the electrical potential difference between two points in a circuit expressed in volts.

Voltage is a scalar quantity. The SI unit of voltage is the volt, such that 1 volt = 1 joule/coulomb.

The easiest way to understand voltage is to use a water analogy. Using a hose as an example, think of voltage as the amount of pressure forcing water through a garden hose. The higher the pressure in the pipe the more water is forced through the pipe each second. The greater the voltage, the greater the flow of electrical current (that is, the quantity of charge carriers that pass a fixed point per unit of time Q=It) through a conducting or semiconducting medium for a given resistance to the flow.

One volt will drive one coulomb (6.24 × 10 18 ) charge carriers, electrons, through a resistance of one ohm in one second.

Voltage can be direct or alternating. A direct voltage maintains the same polarity at all times. So charges always flow in one direction. In an alternating voltage, the polarity reverses direction periodically. The number of complete cycles per second is the frequency, which is measured in hertz (one cycle per second). An example of direct voltage is the potential difference between the terminals of a cell. Alternating voltage exists between the mains positive and negative.