January 1, 2018

2018 ‘A’ Level Physics & Maths Exams Tips & Tricks

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This is the “secret” manual I give to my students, and by sharing this, I hope students and readers will find this useful.

Pre Exam

Sleep well, maintain a healthy body, do necessary revision, memorize necessary definitions and formula. For Physics, the definitions asked usually come up to total 10 to 12 marks and that is one grade or even two grades of difference! There probably isn’t much time to have extensive practice before exams, so focus on revision and going through worked examples or solutions.
MCQ

Physics P1 30 MCQ to be completed in 1 hour. By the 30^th minute mark, you should be at Q15 or thereabout. Do not overspend too much time in the early chapters. Traditionally, chapters on kinematics, dynamics, forces, circular motion, gravitation, oscillations are usually more challenging and take up more time. Some chapters at the back are actually easier, especially modern physics because the questions can’t be too difficult or else no one can do!

If not sure about an MCQ, try to eliminate impossible or wrong answers first, then choose the most likely. If still can’t reach any conclusions, choose option A. Why? Don’t you want to get A!! (unless you are sure option A is not possible!)
Avoiding Careless Mistakes

+Divide by 2π –> /2π should be entered as /(2π), if not entered as a fraction
+Make sure the correct mode of degree or radian is set on the calculator. Most of the physics questions should be on degree.
+For normal cdf, remember to enter $\sigma$ , NOT ${ \sigma }^{ 2 }$ .
+For Binomial distribution, make sure choose the correct one on pdf or cdf.
+Expression like $\ln { ab }$ can be misleading, is it $\ln { \left( ab \right) }$ or $\left( \ln { a } \right) b$ ? Make it clear..
+For calculations that involve many steps like integration (trigo and by parts) or summation, etc., try to check every 3 to 4 steps, because once you finished it may be hard to find where the mistakes were.
Identifying methods or techniques to use

(a) When you see in a summation comprising ( something – something ), then the method of difference is likely to be used.

(b) When an integration involved $\frac { f\left( x \right) }{ g\left( x \right) }$ and $f\left( x \right)$ is one power lesser than $g\left( x \right)$ , then it is likely the ln.

(c) Remember $\int { \sin ^{ 2 }{ \theta d } } \theta$ or $\int { \cos ^{ 2 }{ \theta d } } \theta$ must change to double angle formula;

(d) When events are classified into 2 types with FIXED probability, then it is most likely Binomial distribution.

(e) When revising your Math, try to understand each key characteristics of the various topics.

(f) Similar approach for physics, e.g. 2 sources interference, use Young’s double slit approximation or the general condition on the path difference, don’t use diffraction grating formula. Momentum $p =m\nu$ can be used for all particles with mass, photons got no mass so cannot use, but the de Broglie hypothesis $p=\frac { h }{ \lambda }$ can still be used.

(g) Distinguish between Fleming’s LH and RH rule and how the various formulae are used. The induced emf formula got 2 versions: E=Blv and , use the first one for straight wire, and the second one if the wire forms a shape like a circle, etc.
Intuitive feel of the answer

When you get your answer, you should have a feel of the order of magnitude, whether it makes sense. For example, if you calculate the radius of an atom and get a few mm, you know it is wrong! Or if you find the speed of a particle to be $2 x { 10 }^{ 9 }{ ms }^{ -1 }$ , you know it is wrong as it exceeds the speed of light!
Balance spped and accuracy, and don’t slack till the very end

(a) While speed is important, accuracy is equally important. Do not give up accuracy for speed!
(b) Appropriate time management is crucial. For Math paper which is 3 hours each paper, you should manage your time every hour in such a way that every hour you should try to finish about 35 marks worth of questions.
(c) Take note that marks awarded are not necessarily proportional to the difficulty level.
(d) Must try to do well in Math P1 as that will build confidence.
(e) In an exam, never challenge the question! Unlike practicing your tutorials, you try to challenge the question if don’t get it right. No such luxury in A level exam, if after one attempt, you can’t get it moving, then move on to the next question. Always remember some topics at the back are actually easier, true for physics and math.
(f) The “data analysis “ question in Physics P2 sometimes look difficult but it is actually easy because it tries to explain some new concepts so it appears complicated, just be patient and read through a few times.
(g) The “design and planning” question is usually quite difficult to score high marks. Do not pin too much hope on this portion.
(h) Physics P1 MCQ is probably the last paper, and many would have already started to enjoy prior to Physics P1! It will be a BIG mistake to think that no revision is needed for MCQ. On the contrary, you need to revise EVERYTHING, i.e. every chapter. You will be handsomely rewarded for this last minute revision!
Selecting Question

For Physics P3 Section B, it is 2 questions choose 1. Glance through ALL the 2 questions and choose the one that you are confident to score more marks, not necessarily the one that you are more familiar because it may be harder!
How to deal with a blank mind

When taking a national exam, the stress that comes with the exam and the environment can sometimes cause a blank mind. Particularly if you look at the questions and find that they all look so unfamiliar and you start to panic! Do not allow the state of blank mind to occupy you for too long.
(a) Take a deep breath thru the nose with eyes closed, counting 1 to5 (about 5 seconds); hold the breath, counting 1 to 5; exhale thru the nose, counting 1 to 5; hold the breath, counting 1 to5; Take a deep breath and repeat the cycle 3 times. It will take no more than 2 minutes, but the counting will help to clear your mind and you can later concentrate better.

(b) Once you calm down yourself, you are now in a better position to deal with seemingly difficult questions. First thing search for key words, then link those with concepts and/or formula you know. For example, the word “collision” is likely to bring in concepts of momentum and/or force; “photon” is likely to bring in Planck’s hypothesis and/or photoelectric equation, etc
Others

Make sure you bring spare batteries for your calculator
Please also bring your compass, protractor, etc