Three and four mark questions
These are similar to one- and two-mark questions but you will be expected to write in more depth for three- and four-mark questions.
Edexcel questions courtesy of Pearson Education Ltd.
Sample question 1 - Foundation and Higher
Question
A student uses this circuit to investigate how the current in a filament lamp varies with the potential difference (voltage) across the lamp:
The student takes a range of measurements for the filament lamp.
He plots this graph from his measurements:
Explain how changes in the filament of the lamp account for this graph. [4 marks]
The resistance of the lamp is constant up to 3 V [1]. It is:
\(R = \frac{V}{I}\)
\(= \frac{3}{0.3}\)
\(= 10 \Omega\) [1]
Then as the filament becomes hotter, its resistance increases [1]. This means the current is lower, and the gradient of the line becomes less steep [1].
Sample question 2 - Foundation and Higher
Question
Explain why the temperature of a resistor increases when a current passes through it. [3 marks]
Current is a flow of electrons [1]. The electrons collide with ions in the metal [1], transferring energy into the thermal store of the resistor [1].
Sample question 3 - Foundation and Higher
Question
A kettle is earthed and fitted with a fuse. Explain how this can protect the person using the kettle if there is a fault. [3 marks]
When there is a fault that causes a large current to flow through the earth wire, the fuse melts/blows [1]. This breaks the circuit [1] and prevents a person from getting an electric shock if they touch the kettle [1].
