Virtual Flash Video

The audio can be turned off it is annoys. Here is the Virtual converted to an mp4 if I can get it to work. If people comment and find them useful I can do the rest.



This is the main Radiation post. Start here!

Thanks to Miss Horn for the Radiation Notes. Worked Answers to follow.

From Helpmyphysics


Fusion is the process when two SMALL NUCLEI join to form a LARGER NUCLEI with the production of ENERGY


Fission is the process when two large nuclei split to form two smaller nuclei with the production of energy. This can occur spontaneously or due to a collision with a neutron. Often extra neutrons are produced.

Chain Reaction

When neutrons split nuclei by fission and extra neutrons are produced which can split further nuclei. Large quantities of energy are produced.

Reducing exposure to ionising radiation.

There are 3 groups of category to reduce harm caused by radiation:


Monitor includes things like wearing radiation badges or EPUs, timing how long you are exposed to radiation, checking with radiation counters any contamination on clothes.

Shielding is placing layers of absorbers between you and the source, BEWARE, goggles and a lab coat are great at protecting against alpha but have no effect on gamma. Only thick layers of lead would offer protection against gamma.

Distance. Radiation obeys the inverse square law, as you double the distance from a source the level you are exposed to decreases by ¼ . Using tongs is an effective method of keeping your distance from a source.

When it goes wrong

Chernobyl Nuclear Disaster 1986- Effects and Summary

Chernobyl Surviving Disaster (BBC Drama Documentary)

Chernobyl Questions
  1. What date was the Chernobyl Disaster?
  2. What was the name of the man who hanged himself at the start, who was narrating the story?
  3. Which reactor blew?
  4. What was the cause of the accident?
  5. How many people went to see what had happened?
  6. What happened to the people who saw the hole in the reactor?
  7. What day of the week was the disaster?
  8. What town was evacuated?
  9. How did they drain the water from the reactor?
  10. How did they put out the fire?
  11. What was the reading on the counter when they measured the radiation levels?
  12. Why was this reading misleading and wrong?
  13. What was the real count when it was measured correctly?
  14. What were some of the symptoms of radiation poisoning?
  15. Who was sent to prison for crimes to do with the disaster? (or record how many people went to jail)
  16. Who was president of the USSR when the disaster occurred?
  17. What was the trigger that caused the man to hang himself?
  18. What is the “elephant’s foot?” in the reactor?
  19. Have there been any other nuclear disasters? Can you find out about them and name them?
  20. What other things did you learn about nuclear power stations and radioactivity?
updated June 2019

Week 2: The Maths Bit

Week 2: Significant Figures

You will need to be able to use and understand significant figures in N5 Physics. Don’t worry if you don’t get it straight away, we’ve almost a year to get it right. The video I’ve found is clearer than I could do and sorry it is a bit long, but well worth getting to grips with. What I will add today is a document explaining the importance of significant figures to a physicist, which I will post on here and in the class Notebook section. I wouldn’t watch the hour long video as we need to move on.

  • Watch it here on Youtube : Significant Figures Video
  • Read  and make notes on significant figures: It is in Class Notebook, and on Mrsphysics
  • Read and make notes on Rounding (Sheet to follow)
  • Make sure you’ve checked the answers to the Compendium Questions on Significant Figures. (section 0)
  • I’ll add to the calculator work this week, and you can work through that as soon as you can.

Week 2, part 2. Rounding

You will need to correctly round to the correct number of significant figures in N5 Physics. Again you might not get it straight away, but you’ll get plenty of practice. I’ll do another helpsheet for the Class Notebook.

  • Watch the video on Youtube: Rounding in more detail  it explains the reason for rounding and how it does it
  • For an additional help try this one Rounding Videos This is by the same guy who did the sig fig video.
  • Make notes on rounding: it will eventually be in the class notebook and on MrsPhysics in the N5 maths section.
  • Complete the Sig fig and Rounding Quiz (10 questions). You ought to be able to get at least 7/10. Review the work if you get less than this.

Scientific Notation Week 2 extension

…..but you will need to be able to do this. You will need to know how to do Scientific Notation. I will not test you in this just now, but you should be confident about it by August. Watch this video on YouTube:  Scientific Notation

Make a note on Scientific Notation in your Class Notebook

There will be a sheet this week to help you with this, which will be in the class materials here and in your note book as well, and on this site in the Maths bit.

Significant Figures

Watch the video below on significant figures.

Figure 1: The red and brown is called a counting stick and can only measure to 10 cm.

A picture containing water, clock

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Figure 2: The top part of this metre stick can read to the nearest 1 cm, the bottom to the nearest mm.

When Physicist use numbers it is usually because they have measured something. Significant figures tell us how precise our measurement.

For example a student uses a metre stick to measure the length of a jotter.

A close up of a measure

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If the student measures a jotter with the “counting stick” (in the top picture in the red and brown) which is marked in 10 cm graduations they will not be able to get a very good value. You would get that the jotter was just under 30 cm long but you wouldn’t be able to say much more.

If the student uses a ruler marked in centimetre marks they could say that the jotter was over 29 cm but less than 30 cm and closer to 30 cm than 29 cm, you’d say it was about 30 cm long.

If the jotter was measured with a metre stick marked in millimetres the jotter could be measured as 29.7 cm long

Figure 3 Here is a diagram of the jotter measured with different metre stick.

You need to look at significant figures with rounding which I will cover this week too.

30 cm is one significant figure and means a number between 25 cm and 34 cm which would be rounded to 30 cm. This is how you could record the number if you used the counting stick.

29 cm is two significant figures and means a number between 29.5 cm and 30.4 cm, which would be rounded to 29 cm. This is how you could record the number if you used the metre stick marked in cm only

29.7 cm is three significant figures and means a number between 29.65 cm and 29.74 cm, which would be rounded to 29.7 cm. This is probably the best measurement we should aim to make and to do this we would need a metre stick with millimetre graduations.

29.76 cm is four significant figures and means a number between 29.755 cm and 29.764 cm, it is unlikely that you could measure a jotter to that level of precision as the pages would vary by more than this. You would need a better piece of apparatus than a metre stick to measure this.

How many Significant Figures?

The simple rule is this: Your answer should have no more than the number of significant figures given in the question.

If different numbers in the question are given to a different number of significant figure you should use the number of significant figures in the value given to the smallest number of significant figures.


Question: A rocket motor produces 4,570 N (3 sig fig) of thrust to a rocket with a mass of 7.0 kg (2 sig fig). What is the acceleration of the rocket?

The calculated answer to this question would be 652.8571429 ms-2 . However the least accurate value we are given in the question is the value of the mass. This is only given to two significant figures. Therefore our answer should also be to two significant figures: 650 ms–2 .

You might not think that this makes a difference, but during the SQA Intermediate 2 paper in 2006 Q25 was written to test significant figures.