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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 68 · 40 questions
TalentJR

Remember (Find the topic, use the formula): Find the topic and the formula: V = I × R, I = V ÷ R, R = V ÷ I, P = V × I, units = W × h ÷ 1000. Change mA to A and kΩ to Ω before using a formula. Check: put your answer back into the formula.

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  1. 1.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
  2. 2.🌈 A resistor has the colour bands white, green, black. What is its value (in ohms)?
  3. 3.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = V + I (c) R = I ÷ V (d) R = V ÷ I
  4. 4.🧩 Which part changes electrical energy into sound? (a) a buzzer (b) a diode (c) a resistor (d) a capacitor
  5. 5.True or false: a fuse blows if current is high. (a) True (b) False
  6. 6.🔺 A current of 2 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  7. 7.🧩 A capacitor in a circuit can … (a) spin a wheel (b) store charge briefly (c) measure heat (d) make light
  8. 8.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 ampere (c) 1 kilowatt-hour (kWh) (d) 1 volt
  9. 9.🧮 Resistors of 68 Ω, 220 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
  10. 10.⚡ Power tells us … (a) the colour of light (b) energy used each second (c) the size of a cell (d) the length of a wire
  11. 11.🔺 A current of 0.2 A flows when 0.4 V is joined across a resistor. What is its resistance (in ohms)?
  12. 12.⚡ Which formula gives electric power? (a) P = V × I (b) P = I ÷ V (c) P = V + I (d) P = V ÷ I
  13. 13.Which of these is measured in watts (W)? (a) power (b) the push of a cell (c) voltage (d) resistance
  14. 14.🔺 A current of 1.5 A flows when 15 V is joined across a resistor. What is its resistance (in ohms)?
  15. 15.📏 How many milliamperes (mA) is 0.69 A?
  16. 16.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
  17. 17.True or false: to leave fridge door open saves electricity. (a) True (b) False
  18. 18.True or false: the flow of charge is measured in volts (V). (a) False (b) True
  19. 19.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it changes colour (c) it makes a sound (d) it does not light
  20. 20.⚡ A 3 W device works on 1.5 V. What current does it take (in amperes)? =
  21. 21.🧮 Resistors of 150 Ω, 33 Ω, 470 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
  22. 22.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  23. 23.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 25 % (c) 5 % (d) 50 %
  24. 24.🔺 A 5 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  25. 25.🔺 A current of 0.25 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  26. 26.🧾 A 250 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
  27. 27.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
  28. 28.🧾 Which lamp gives the same light for the least power? (a) a candle (b) an LED lamp (c) an oil lamp (d) a filament bulb
  29. 29.🔺 A current of 3 A flows when 9 V is joined across a resistor. What is its resistance (in ohms)?
  30. 30.True or false: a diode smooths a wobbly supply. (a) True (b) False
  31. 31.True or false: the ammeter measures current. (a) True (b) False
  32. 32.💡 Does it save or waste electricity to use old filament bulbs? (a) wastes electricity (b) saves electricity
  33. 33.🌈 Which band is read first on a resistor? (a) any band (b) the one nearest an end (c) the widest gap (d) the gold band
  34. 34.Which of these is measured in ohms (Ω)? (a) resistance (b) the flow of charge (c) power (d) voltage
  35. 35.🧾 A 200 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
  36. 36.True or false: voltage is measured in watts (W). (a) False (b) True
  37. 37.What does a resistor do? (a) limits the current (b) makes things spin (c) beeps for an alarm (d) is a resistance knob
  38. 38.True or false: power is measured in amperes (A). (a) True (b) False
  39. 39.Which of these is measured in volts (V)? (a) energy used each second (b) the push of a cell (c) resistance (d) current
  40. 40.True or false: a transistor boosts a small signal. (a) True (b) False

Answer key

  1. 1150
  2. 95
  3. R = V ÷ I
  4. a buzzer
  5. True
  6. 10
  7. store charge briefly
  8. 1 kilowatt-hour (kWh)
  9. 308
  10. energy used each second
  11. 2
  12. P = V × I
  13. power
  14. 10
  15. 690
  16. voltmeter
  17. False
  18. False
  19. it does not light
  20. 2
  21. 721
  22. 100
  23. 5 %
  24. 50
  25. 0.75
  26. 1.25
  27. 460
  28. an LED lamp
  29. 3
  30. False
  31. True
  32. wastes electricity
  33. the one nearest an end
  34. resistance
  35. 0.8
  36. False
  37. limits the current
  38. False
  39. the push of a cell
  40. True

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