Quick answer: In a series circuit the current is the same everywhere and the voltages add up to the supply; in a parallel circuit every branch has the full supply voltage and the branch currents add up. This Physics 9-10 test on electrical power has 8 questions worth 20 marks, to do in 45 minutes: series and parallel, series calculation and parallel calculation. The mark scheme is on a separate page; free printable PDF.
This test has 8 questions worth 20 marks in total. Use a calculator, show every step, and write units on your answers. You have 45 minutes.
Level: Physics grades 9-10 (GCSE · IGCSE · O Level · Class 9-10) · Curriculum: GCSE P2, HS-PS3-3
Question 1 Series and parallel (2 marks)
State two differences between a series circuit and a parallel circuit.
Question 2 Series calculation (3 marks)
The circuit shows two resistors in series on a 9.0 V cell.
- Calculate the total resistance. (1 mark)
- Calculate the reading on the ammeter. (1 mark)
- Calculate the potential difference across the 40 Ω resistor. (1 mark)
Question 3 Parallel calculation (3 marks)
A 24 Ω resistor and an 8.0 Ω resistor are connected in parallel across a 12 V supply.
- Calculate the current in each resistor. (2 marks)
- Calculate the total current drawn from the supply. (1 mark)
Question 4 Hair dryer fuse (2 marks)
A hair dryer is rated 1.8 kW at 230 V. Fuses of 3 A, 5 A and 13 A are available.
- Calculate the current. (1 mark)
- Choose the correct fuse. (1 mark)
Question 5 Cost of an oven (3 marks)
An oven of power 1.5 kW is used for 2.5 hours. Electricity costs 28 p per kWh.
- Calculate the energy used in kWh. (1 mark)
- Calculate the cost in pounds. (2 marks)
Question 6 Role of the earth wire (3 marks)
Explain how the earth wire and the fuse together protect a user if a live wire touches the metal case of a toaster.
Question 7 Power in a resistor (2 marks)
A current of 3.0 A flows in a resistor of 8.0 Ω. Calculate the power transferred.
Question 8 Lamps in a house (2 marks)
Explain why adding more lamps in parallel does not dim the others, but adding more lamps in series does.
