HKDSE (Hong Kong) · Physics

Electricity and Magnetism

30 practice questions, each with the answer and an explanation.

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Random questions from this topic, one at a time. You see the answer and the explanation straight after each one.

All 30 questions

  1. A current of 0.5 A flows through a 6 Ω resistor. What is the potential difference across it?
  2. A current of 4 A flows through a 10 Ω resistor. What is the potential difference across it?
  3. A current of 4 A flows through a 12 Ω resistor. What is the potential difference across it?
  4. A current of 3 A flows through a 10 Ω resistor. What is the potential difference across it?
  5. A 4 Ω resistor and a 12 Ω resistor are connected in parallel. What is the total resistance?
  6. Resistors of 4 Ω, 6 Ω and 4 Ω are connected in series. What is the total resistance?
  7. Resistors of 6 Ω, 3 Ω and 4 Ω are connected in series. What is the total resistance?
  8. Resistors of 3 Ω, 3 Ω and 4 Ω are connected in series. What is the total resistance?
  9. A 3 Ω resistor and a 12 Ω resistor are connected in parallel. What is the total resistance?
  10. A 4 Ω resistor and a 6 Ω resistor are connected in parallel. What is the total resistance?
  11. A 4 Ω resistor and a 3 Ω resistor are connected in parallel. What is the total resistance?
  12. A 6 Ω resistor and a 12 Ω resistor are connected in parallel. What is the total resistance?
  13. An appliance connected to a 220 V supply draws a current of 10 A. What is its power?
  14. An appliance connected to a 110 V supply draws a current of 5 A. What is its power?
  15. An appliance connected to a 220 V supply draws a current of 2 A. What is its power?
  16. An appliance connected to a 110 V supply draws a current of 0.5 A. What is its power?
  17. A 1000 W heater is used for 4 hours. The electricity tariff is HK\$1.1 per kWh. What is the cost of using the heater?
  18. A 1000 W heater is used for 6 hours. The electricity tariff is HK\$1.1 per kWh. What is the cost of using the heater?
  19. A 3000 W heater is used for 2 hours. The electricity tariff is HK\$1.1 per kWh. What is the cost of using the heater?
  20. A 1000 W heater is used for 4 hours. The electricity tariff is HK\$1.2 per kWh. What is the cost of using the heater?
  21. A current of 0.5 A flows for 120 s. How much charge passes?
  22. A current of 2 A flows for 20 s. How much charge passes?
  23. A current of 0.5 A flows for 10 s. How much charge passes?
  24. An ideal transformer has 100 turns in the primary coil and 50 turns in the secondary coil. The primary voltage is 240 V. What is the secondary voltage?
  25. An ideal transformer has 1000 turns in the primary coil and 10000 turns in the secondary coil. The primary voltage is 220 V. What is the secondary voltage?
  26. An ideal transformer has 200 turns in the primary coil and 20 turns in the secondary coil. The primary voltage is 240 V. What is the secondary voltage?
  27. An ideal transformer has 100 turns in the primary coil and 500 turns in the secondary coil. The primary voltage is 110 V. What is the secondary voltage?
  28. In a household circuit, which wire should the fuse be connected in?
  29. What is the purpose of the earth wire connected to the metal case of an appliance?
  30. When two identical bulbs are connected in parallel across a battery, compared with one bulb alone each bulb is

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