1. 1
   A kettle is connected to the 230 V mains supply. When switched on, a current of 10 A flows through the heating element while it boils a full kettle of water, which takes 3 minutes.

   (a)

   What is the power rating of the kettle when it is operating, given the current and voltage in the scenario?

   [1 mark]

   • A23 W
   • B230 W
   • C2300 W
   • D23000 W

   (b)

   Which energy transfer takes place in the kettle's heating element while the water is boiling?

   [1 mark]

   • AElectrical to kinetic
   • BElectrical to thermal
   • CChemical to electrical
   • DElectrical to light

   (c)

   Calculate the total energy transferred to the water while the kettle boils for 3 minutes, using the power found in part (a). Give your answer in joules.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   An electric drill on a construction site is connected to the 230 V mains supply. When operating at full power, a current of 5 A flows through the drill. The site electrician must fit a fuse of suitable rating, chosen from 3 A, 5 A and 13 A cartridge fuses, into the drill's plug.

   (a)

   What is the power of the drill when it operates at full power?

   [1 mark]

   • A1150 W
   • B46 W
   • C235 W
   • D11500 W

   (b)

   Which fuse rating should the electrician fit in the drill's plug?

   [1 mark]

   • A3 A
   • B5 A
   • C13 A
   • D30 A

   (c)

   Explain why fitting a fuse of the correct rating is important for the safety of anyone using the drill.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A hospital keeps a portable patient monitor, rated at 0.06 kW, connected to the mains for 8 hours during each night shift. Electricity costs the hospital 0.45 AED per kilowatt-hour.

   (a)

   Calculate the energy transferred by the monitor, in kilowatt-hours, over one 8-hour night shift.

   [3 marks]

   (b)

   The monitor is used in this way for 30 night shifts. Calculate the total cost of running the monitor over the 30 shifts.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A secondary school is reviewing its electricity bills because its air conditioning units run for long periods each day. The head teacher wants to understand the physics behind the energy transfers and costs involved, and to explore ways of reducing electricity usage without affecting comfort in classrooms.

   (a)

   Explain, using appropriate equations and units, how the energy transferred by the school's air conditioning units depends on their power rating and running time, and describe how the head teacher could use this to estimate the school's monthly electricity cost.

   [6 marks]

   (b)

   Evaluate two methods the school could use to reduce its electricity costs from air conditioning, explaining the physics reasoning behind each and any drawbacks of each method.

   [6 marks]

   Total for question 4: 12 marks

End of questions