Three to four mark questions
These are similar to one to two mark questions but you will be expected to write in more depth for three to four mark questions.
The answers here give lists of valid points that could be included in your answer.
This page contains AQA material which is reproduced by permission of AQA.
Sample question 1 - Foundation
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Question
A student rubs an acetate rod with a cloth.
The diagram above shows the charges on the acetate rod and cloth before and after rubbing.
Explain how rubbing an acetate rod with a cloth causes the rod and cloth to become charged. [4 marks]
Friction causes electrons to move from the rod and on to the cloth. The charge on the rod is positive, as it has lost electrons. The charge on the cloth is negative, as it has gained electrons.
The key idea to include in this answer is that the movement of electrons is the reason for the rod and cloth becoming charged.
Sample question 2 - Foundation
Question
The equation which links current, potential difference and resistance is:
potential difference = current × resistance
Calculate the potential difference across the battery in the circuit below. [3 marks]
Potential difference = 12 V
Potential difference = current × resistance
= 0.4 A x (20 Ω + 10 Ω)
= 0.4 A x 30 Ω
= 12 V
Show all stages of working out and include units in the answer.
Sample question 3 - Higher
Question
A Van de Graaff generator is used to investigate static electricity.
Before it is switched on, the metal dome has no net charge. After it is switched on, the metal dome becomes positively charged.
Explain how an uncharged object may become positively charged. [3 marks]
There is friction between two insulating materials. The friction causes electrons to be rubbed off one material and onto the other. Losing electrons leaves the object positively charged.
Sample question 4 - Higher
Question
An electrician is replacing an old electric shower with a new one.
If the electrician touches the live wire when the mains electricity supply is still on, she will receive an electric shock.
Explain why. [4 marks]
The potential of the live wire is 230 V. The potential of the electrician is 0 V. Because there is a large potential difference between the live wire and the electrician, charge/current passes through the electrician's body and gives her an electric shock.