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.
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The equation which links current, potential difference and resistance is:
potential difference = current × resistance
Calculate the potential difference across the battery in the circuit in Figure 3. [3 marks]
Potential difference = current × resistance 
= 0.4 A x (20 Ω + 10 Ω) 
= 0.4 A x 30 Ω
Potential difference = 12 V 
Show all stages of working out and include units in the answer.
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 .