Mojza Blog
A Guide To A Level Physics Practicals
by Muhammad Haris | 17 Oct 2025
A Level Physics can feel like a mix of problem-solving and detective work. From setting up complex electrical circuits to timing oscillations, the practical side of the course brings the theories from class into real life. This meticulously crafted guide is designed to walk you through the subject matter, highlight common pitfalls, and share tips that make your A Level Physics practical exam a walk in the park.
Paper Pattern
Your practical component for Physics is your Paper 3. It’s worth 40 marks and allotted a time of 2 hours, consisting of 2 questions each worth 20 marks.
Question 1
The first question on your Physics Practical will always require you to set-up your apparatus as shown on a diagram, and to use it to obtain a set of readings. These will then be plotted on a graph, for which you will draw a line of best fit and find its gradient.
The experiment described may, for example, have you calculate the time period for oscillations, often from a seemingly odd apparatus.
On the other hand, you can also be asked to set up an electrical circuit. This includes the use of wires, crocodile clips, power supplies, switches—the whole nine yards. You will then collect readings for voltage or current output, and once again, plot them on a graph. Here’s a quick tutorial for electrical circuitry to get you started.
Some important guidelines for making this table of results, are:
- Include columns for all required quantities, making sure to add their respective units after a ‘slash’ (/).
- The question will also often ask you to include additional quantities that you will have to calculate yourself, such as the reciprocal of measured length, 1/L. Make sure to not miss them in a hurry!
- Make sure the number of significant figures across all your calculated measurements is the same or one more than the raw values; and know the usual number of decimal places required for various instruments when noting values.
- Draw the table with scaled lines using a pencil.
When forming your graph, as well as your line of best fit, remember:
- Choose an appropriate scale for both axes. Avoid an ‘odd’ scale, in which each unit is separated by a weird number like 0.37.
- Your graph should cover more than half of the provided space, both length and width-wise. Again, choosing an appropriate scale for both axes would help with this.
- Your plotted points should never be big blobs; try to keep them small and neat, using crosses or circles, as not doing so will cost you marks.
- When making your line of best fit, try to keep the same number of points above and below the line; make sure your line shows the trend of your graph. Don’t force your line through the first and last plotted point, and don’t force it through the origin, as this holds no importance in the marking criteria.
- When calculating the gradient of your line of best fit, make sure to use points far away from each other on the line, covering more than half the line.
Question 2
For the second question on the exam, you’ll then have to set up a different apparatus according to the diagram shown, and collect some more readings.
However, the difference here from the previous question is that this one is more analysis based. Moreover, its structure is quite straightforward, with the very same sub-parts always showing up on every paper. Here are some tips to keep in mind for every other sub-part that can show up:
Measuring Quantities and Significant Figures
When asked to measure a quantity for your experiment, such as length or time, make sure to always measure for the quantity twice and plug in their mean as your final answer. Additionally, make sure to keep a constant number of significant figures across all your measurements’ values.
When asked to justify the number of significant figures in your values, make sure to write that this was the least number of significant figures across all your values.
The ‘K’ Constant and Proving Suggested Relationships
You’ll then be asked to usually calculate 2 values for a constant ‘k’, using your measurements and an unseen formula given to you in the question. Pull out your calculators. Plug and chug. Simple enough.
Next, you’ll always be presented with a value for the percentage uncertainty between your 2 calculated readings of ‘k’, usually 10% or 15%. The question will ask you to determine whether or not ‘your results support the suggested relationship’. Remember this as your cue to simply calculate the percentage difference between your values of ‘k’. If this difference is less than the given percentage uncertainty, write that your results do support the conclusion. If the difference is more than 15%, write that they do not. Note that not being able to prove the suggested relationship doesn’t cost you marks; rather, what the examiner wants to see is the above mentioned working. So don’t stress over it.
Identifying Sources Of Uncertainty and Suggesting Improvements
Finally, the last part of question 2 will always ask you to suggest 4 sources of uncertainty, or any limitations, in the experimental procedure.
A limitation that ALWAYS applies to the question, and should hence be memorized, is that the number of sets of values we have used (almost always being 2) are insufficient to draw a viable conclusion about our experiment. Make sure to write this point as it’s always in the mark scheme.
Furthermore, avoid writing low-effort and straightforward suggestions such as simply saying that there was a chance of your scale readings being affected by parallax error; such points usually don’t get awarded marks. Instead, try to really think about your procedure; what was a part of carrying out this experiment that could cause your measurements to be erroneous? Was some part of the apparatus hard to set up that could’ve had an easy fix? Did something keep falling over while setting everything up? Thinking critically about your procedure like this would help in coming up with good suggestions for this sub-part.
Next, you will then be asked to suggest 4 improvements in response to the same limitations you suggested above. Once again, another point that can ALWAYS be added here, referring to the same one mentioned above, is to get at least 6 sets of readings from your experiment and plot them on a graph to compare your results and get more viable conclusions.
An example of a source of error in an experiment requiring you to measure the time period for oscillations could be this:
“Human reaction time while using the stopwatch to measure the time period for oscillations may act as a source of uncertainty in the value for time period.”
The suggested improvement for this could be something like this:
“Record the oscillations on a video playback camera, and review its footage frame by frame to get an exact, accurate value for the time period.”If all of this sounds a bit overwhelming, here’s a video to slowly take you through the entire question 2 format while solving a past paper!
General Tips
Time management is crucial in a practical exam. It’s easy to get caught up in repeating a step or rechecking your results, but remember that every minute counts. Plan your work in stages: set a target for when you should finish setting up, when to start taking results, and when to move on to calculations or graph plotting. This will help you avoid a last-minute rush and ensure you have enough time to check your answers before handing in your paper.
Always place your exam paper or any written material on a clean, dry part of your bench, well away from chemicals, water, or flame sources. Spilled liquids or stains can damage your paper, making it unreadable for examiners, and in worst cases, you could lose marks. Keeping your workspace organized will also reduce confusion, minimize accidents, and help you focus better.
Glassware, sharp instruments, and electrical equipment are delicate and can be hazardous if mishandled. Always set up your apparatus steadily, avoid unnecessary movements that could knock things over, and check that everything is clamped securely before starting.
One of the most common mistakes in practical exams is forgetting to include units in your tables. Every column should have both the quantity and its unit clearly labeled, for example: Time / s or Volume of gas / cm³. Omitting these steps cost you arguably the easiest marks on the paper.
All the nerd-talk aside, in the end you also have to accept that practicals are quite prone to mishaps and accidents; you may spill some liquid all over your question paper, or your electrical circuit might just refuse to turn on and show a reading. Thankfully, paper 3 only holds a weightage of 11.5% on your final A level grade, so calm yourself down if you mess something up on the practical, and be at ease about your results if you did well on the theoretical components, since those hold the most weightage.
Good luck with your A levels, people! You’ve got this!
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