GCSE Standard Questions: Electricity in the Home
Q3. The diagram shows a mobile phone battery being charged using solar cells. The useful power output of the solar cells is 2.5 W.
(a) The efficiency of the solar cells is 40%. Calculate the total power input to the solar cells.
(b) The mobile phone battery can store 36 kJ of energy and was initially uncharged. Calculate the minimum time, in hours, it would take to fully charge the mobile phone battery using these solar cells.
(c) Explain why the power output of the solar cells may be lower than 2.5 W
(d) Explain why the time taken to recharge this mobile phone battery using these solar cells depends on whether the phone is switched on or off.
(Total 9 marks)