A mobile phone battery has a potential difference of 4.0 V.
When fully charged, the battery can transfer 54 kJ of energy.
When the phone is being used to make calls, the current is 250 mA.
Calculate the power of the phone when it is being used to make calls.
Calculate the number of hours that a fully charged battery can be used to make calls.
When the phone is used to play a game, the current increases to 600 mA and the phone becomes warm.
Explain why the phone becomes warmer when the current is greater.
Calculate the number of hours that a fully charged battery can be used to play the game.
105 exam-style questions on Edexcel GCSE Physics 10.3 Electrical energy and power, covering 10.3.1 The heating effect of an electric current, 10.3.2 Reducing energy transfer in wires, 10.3.3 Advantages and disadvantages of the heating effect, 10.3.4 Energy transferred by an electrical circuit, 10.3.5 Electrical power, and 10.3.6 Energy transfers in domestic devices. Each one has a worked solution and a mark scheme showing where the marks go.