An electric sewing machine draws a current of 1.2 A from a 230 V supply. Unwanted processes transfer energy at a rate of 96 W. The machine is used for 4.0 min. How much energy is transferred usefully during this time?
66.2 kJ66.2\ \mathrm{kJ}66.2 kJ
0.720 kJ0.720\ \mathrm{kJ}0.720 kJ
43.2 kJ43.2\ \mathrm{kJ}43.2 kJ
23.0 kJ23.0\ \mathrm{kJ}23.0 kJ
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.