AQA GCSE Physics Past Papers

Common mistake: Significant confusion exists regarding the direction of current in diodes/LEDs and the difference between the motor effect and the generator effect.

How to solve it: Remember that a diode only allows current in the "forward" direction. For magnetism, use Fleming's Left-Hand Rule for the motor effect (input current, output motion) and the term "generator effect" for induced potential difference (input motion, output current)

Common mistake: Students often incorrectly state that radiation "ionizes cells," whereas ionization actually occurs at the atomic level. There is also frequent confusion between nuclear fission (splitting a nucleus) and nuclear fusion (joining nuclei).

How to solve it: Use precise language—radiation ionizes atoms, which then leads to damage in cells or DNA. Remember that fission involves a nucleus splitting into two daughter nuclei, while fusion involves nuclei joining to form a larger, heavier nucleus.

Common mistake: A common misconception is that a resultant force of zero means an object must be stationary, forgetting that it could also be moving at a constant speed. In terminal velocity questions, students often fail to account for the increasing effect of air resistance as speed increases.

How to solve it: If the resultant force is zero, the object's velocity is constant. For falling objects, explain that air resistance increases with velocity until it balances weight, resulting in zero acceleration.

Common mistake: Students often struggle to distinguish between the motor effect (input current, output motion) and the generator effect (input motion, output current). In transformers, many wrongly believe the iron core is used because it conducts electricity, rather than for its magnetic properties.

How to solve it: Use Fleming's Left-Hand Rule specifically for the motor effect. In transformers, state that the iron core is used because it is easily magnetized to transfer the magnetic field between the coils.

Common mistake: In questions involving the reflection or refraction of light, students often fail to draw a normal line or use a protractor to measure angles accurately. This leads to incorrect paths for light rays.

How to solve it: Always draw a dotted "normal" line at 90 degrees (perpendicular) to the surface at the exact point where the light ray hits it. All angles of incidence, reflection, and refraction must be measured from this normal line, not from the surface itself.