Practise Energy transfers in everyday appliances. 12 exam-style questions plus unlimited generated ones on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
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Write down the equation that links charge flow (Q), energy transferred (E) and potential difference (V).
E = Q V
Write down the equation that links energy transferred (E), power (P) and time (t).
E = P t
A 100 W lamp is switched on for 10 s. Calculate the energy transferred.
1000 J
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy4 marks
Everyday electrical appliances are designed to bring about energy transfers.
(a) An electric kettle has a power of 2000 W. It is switched on for 180 s. Calculate the energy transferred by the kettle. Use the equation: energy transferred = power × time[2]
(b) An electric fan is switched on. Which energy store of the fan blades increases? Tick (✓) one box.[1]
chemical
elastic potential
kinetic
nuclear
(c) The energy transferred by an appliance depends on the power of the appliance and on one other factor. What is the other factor? Tick (✓) one box.[1]
how long the appliance is switched on for
the length of the cable
the mass of the appliance
the colour of the appliance
Show the answer and mark scheme
(a)Answer: 360 000 J
E = 2000 × 180
E = 360 000 (J)
(b)Answer: kinetic
(c)Answer: how long the appliance is switched on for
Question 2Medium7 marks
Energy is transferred when charge flows through electrical appliances.
(a) Write down the equation that links charge flow (Q), energy transferred (E) and potential difference (V).[1]
(b) A charge of 5.0 C flows through a motor. The potential difference across the motor is 12 V. Calculate the energy transferred.[2]
(c) An electric shower has a power of 9.0 kW. It is used for 20 minutes each day. The energy transferred in kilowatt-hours (kWh) is the power in kilowatts multiplied by the time in hours. Calculate the energy transferred by the shower each day in kilowatt-hours.[2]
(d) Electricity costs 28p per kWh. Calculate the cost of using the shower for 7 days.[2]
Show the answer and mark scheme
(a)Answer: E = Q V
E = Q × V / energy transferred = charge flow × potential difference
(b)Answer: 60 J
E = 5.0 × 12
E = 60 (J)
(c)Answer: 3.0 kWh
E = 9.0 × (20 ÷ 60) / 9.0 × 0.333
E = 3.0 (kWh)
(d)Answer: 588p (£5.88) p
3.0 × 7 × 28
588 (p) / £5.88
Question 3Hard6 marks
A car battery has a potential difference of 12 V. It is charged with a constant current of 8.0 A for 5.0 hours.
(a) Calculate the charge that flows into the battery while it is being charged.[2]
(b) Calculate the energy transferred to the battery.[2]
(c) The charger is 75% efficient. Calculate the total energy drawn from the mains to charge the battery.[2]