12 top tips for IB Physics Option C exam success

Success in your IB Physics Option C exam for Imaging depends as much on knowing what not to do as it does on knowing the material. Each exam cycle students lose valuable points for making simple errors. In this article, experienced IB teacher and our author, Hugh Duncan, shares his 12 top tips for IB Physics C exam success, taken from his Peak IB study guide, Physics Option C: Imaging Standard and Higher Level.

Hugh’s tips will help you understand mistakes students commonly make on their IB Physics Imaging exam – read them, know them, share them, avoid them. In doing so, you’ll give yourself the best opportunity for IB exam success.

IB Physics Option C exam mistakes to avoid

1. Diagrams drawn in pen: All ray diagrams should be drawn with a sharp pencil and ruler! Marks are given for accuracy and presentation. Don’t just put letters like W unless the question says weight is W, or otherwise include a key. Learn the parts, especially of standard diagrams.

2. Virtual rays drawn solid: It is usual to draw real rays as solid lines and virtual rays as dotted lines.

3. Rays drawn without arrow heads: This is a serious crime! A ray drawn without an arrowhead is just a line. The arrowhead shows the direction light is travelling. Don’t put rays coming OUT of an observer’s eye either – that only happens in sci fi movies. Light rays ENTER the eye.

4. Ignoring the negative nature of unreal distances: The usual convention is that real distances are positive, virtual distances are negative. Forgetting negative signs will ruin answers involving lenses. Real is positive.

5. Using incorrect units or no units at all with your answers: Often wavelengths of light are quoted in nanometres, or even micrometres, yet they must be converted to metres. Similarly, lens problems can use centimetres. Most answers in optics will need units, such as distances, but some things, such as magnification or number of fringes, have no units.

6. Denser medium is wrongly identified: When refraction is taking place, light bends more to the normal in the denser medium.

7. Answers are not rounded: Look at the number of sig fig in each number given in the question. The final answer will have the same as that with the least number of sig fig. If one is multiplying or dividing say 1.2, 317, 0.03457 then the final answer will have only 2 sig fig as 1.2 has only 2 sig fig. If one is adding or subtracting then one rounds to the least accurately known position. For example if the numbers used are 345, 2.3, 1023.23, then the final answer must be rounded to the nearest whole number as 345 is the least accurately known.

8. Conversion to the correct units: Often X-ray wavelength is given in nanometres and like all quantities must be converted to the fundamental units of kg, m, s, etc.

9. Misuse of characters: GDCs are complex devices and should be used every day to maintain familiarity. Common mistakes include forgetting brackets and not checking that angles are in degrees or radians.

10. Converting units: often the units given are not converted into the units required for calculation; lengths should be n metres, time in seconds etc. but sometimes there are exceptions.

11. Working out: The present style of marking for examination questions allows several points for showing working out. For example, there may be four points for calculation and three are for the working out, only one for the final answer. Imagine the final answer is wrong for some silly reason, but all the working out is correct; it is possible to score 3 out of 4, which is 75% and pretty much an IB grade 7! Can you afford to miss out on that chance?!

12. Terms confused: There are several similar quantities, such as exposure, absorbed dose, quality factor and does equivalent. There is no easy way, just learn them.

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What next?

Now that you know the common errors to avoid making in your IB Physics Option C exam, you can get started with organising the rest of your study and revision process. You’ll need to think about how much time you have to devote to your study practice and exam revision, not just for Physics but for all of your IB subjects – it’s a big balancing act.

If you’re looking for a little guidance on how to motivate yourself and avoid procrastinating, check out our article on 14 ways to avoid procrastination in the IB Diploma. For Physics specific advice, head to our IB Physics subject page where you’ll find additional free Physics resources as well as links to our entire series of IB Physics study guides.