1. 1
   A café owner is comparing two kettles. Kettle X is connected to the 230 V mains supply and draws a current of 10 A. Kettle Y has a heating element of resistance 20 Ω and draws a current of 8 A.

   (a)

   A kettle is connected to the 230 V mains supply and draws a current of 10 A. Which equation should be used to calculate its electrical power?

   [1 mark]

   • AP = V/I
   • BP = VI
   • CP = I/V
   • DP = V + I

   (b)

   Which equation should be used to calculate the power dissipated by Kettle Y, given its resistance and current?

   [1 mark]

   • AP = I²R
   • BP = IR²
   • CP = R/I
   • DP = I/R²

   (c)

   Calculate the power of Kettle X and the power of Kettle Y. State which kettle transfers energy faster.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A student is investigating the running cost of a 2000 W hairdryer used every morning for 6 minutes, and compares it with a phone charger that transfers a charge of 3600 C while moving it through a potential difference of 5 V.

   (a)

   Which equation directly links the energy transferred by an appliance to its power and the time it is switched on for?

   [1 mark]

   • AE = t/P
   • BE = P/t
   • CE = Pt
   • DE = P + t

   (b)

   Which equation should be used to calculate the energy transferred by the phone charger, given the charge moved and the potential difference?

   [1 mark]

   • AE = Q/V
   • BE = Q + V
   • CE = V/Q
   • DE = QV

   (c)

   Calculate the energy transferred by the hairdryer in one 6-minute use, and the energy transferred by the phone charger in the scenario described.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A factory uses an electric motor to power a hoist that lifts heavy loads. The motor is connected to a 230 V supply and draws a current of 15 A whenever it is operating, and the factory manager wants to know the energy cost of running it for a full shift.

   (a)

   An electric motor in a factory hoist lifts a load using a 230 V supply and draws a current of 15 A. Calculate the electrical power supplied to the motor, and calculate the energy transferred to the motor if it runs continuously for 2 hours.

   [3 marks]

   (b)

   The factory manager wants to compare two different hoist motors that both do the same job. Motor A has a lower resistance than Motor B. Explain, using the equation P = I²R, why Motor B (with the higher resistance) is likely to become hotter than Motor A when the same current flows through both.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A hospital is comparing two models of patient-monitoring equipment, Model P and Model Q, that perform an identical task but are designed with different internal current ratings for the same power output, and the procurement team wants to understand which design wastes less energy as heat.

   (a)

   A hospital is choosing between two models of patient-monitoring equipment that both perform the same task. Model P operates at a lower current than Model Q for the same power output. Using the equations P = VI and P = I²R, explain how power, potential difference, current and resistance are related in electrical appliances, and explain why designing equipment to operate at a lower current (for the same power) can reduce energy wasted as heat in its internal wiring.

   [6 marks]

   (b)

   Evaluate the claim made by a manufacturer that 'a higher-power appliance always transfers more total energy than a lower-power appliance.' Use the equation E = Pt and a specific example involving time to support your evaluation.

   [6 marks]

   Total for question 4: 12 marks

End of questions