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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 591 · 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.🧮 Resistors of 470 Ω, 150 Ω, 220 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
  2. 2.⚡ A 3 W device works on 12 V. What current does it take (in amperes)? =
  3. 3.🌈 In the resistor colour code, which number does red stand for?
  4. 4.🔺 A current of 3 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  5. 5.📏 Which unit measures the flow of charge? (a) ohm (Ω) (b) ampere (A) (c) volt (V) (d) watt (W)
  6. 6.🧩 Which part changes electrical energy into movement? (a) a fuse (b) a motor (c) an LED (d) a resistor
  7. 7.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 100 (b) 1000 (c) 10 (d) 1024
  8. 8.🔺 A current of 0.25 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  9. 9.🌈 In the resistor colour code, which number does grey stand for?
  10. 10.True or false: on an LED, the round-side leg is the cathode (−). (a) False (b) True
  11. 11.📏 In the water-pipe picture of a circuit, current is like … (a) the water pressure (b) a narrow pipe (c) the flow of water (d) the pipe colour
  12. 12.True or false: on an LED, the longer leg is the anode (+). (a) False (b) True
  13. 13.🌈 A resistor has the colour bands green, white, yellow. What is its value in kilo-ohms (kΩ)? =
  14. 14.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 volt (c) 1 ampere (d) 1 kilowatt-hour (kWh)
  15. 15.Which of these is measured in amperes (A)? (a) energy used each second (b) the push of a cell (c) current (d) voltage
  16. 16.⚡ A device works on 3 V and takes 0.2 A. What is its power (in watts)? =
  17. 17.🔺 A current of 2 A flows when 16 V is joined across a resistor. What is its resistance (in ohms)?
  18. 18.🔺 A current of 1 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  19. 19.True or false: resistance is measured in ohms (Ω). (a) False (b) True
  20. 20.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) smaller (c) stay the same (d) zero
  21. 21.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  22. 22.🔺 A current of 0.1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.🧩 A capacitor in a circuit can … (a) measure heat (b) spin a wheel (c) store charge briefly (d) make light
  24. 24.🔺 A 2.2 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
  25. 25.🌈 In the resistor colour code, which number does blue stand for?
  26. 26.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V ÷ I (c) P = V + I (d) P = V × I
  27. 27.💡 Does it save or waste electricity to switch off empty rooms? (a) wastes electricity (b) saves electricity
  28. 28.🔺 A current of 1 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  29. 29.True or false: to leave fridge door open saves electricity. (a) False (b) True
  30. 30.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
  31. 31.🔺 A current of 0.1 A flows when 0.4 V is joined across a resistor. What is its resistance (in ohms)?
  32. 32.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V ÷ R (c) I = V + R (d) I = V × R
  33. 33.🔺 A current of 0.25 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  34. 34.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  35. 35.True or false: the ammeter is joined across a part. (a) False (b) True
  36. 36.⚡ A device works on 12 V and takes 0.2 A. What is its power (in watts)? =
  37. 37.⚡ A 0.75 W device works on 1.5 V. What current does it take (in amperes)? =
  38. 38.🔍 Which is the odd one out? (a) leave the TV on standby (b) use LED lamps (c) switch off empty rooms (d) set the AC to 24 °C
  39. 39.🧾 A 2000 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
  40. 40.⚡ A 0.3 W device works on 3 V. What current does it take (in amperes)? =

Answer key

  1. 890
  2. 0.25
  3. 2
  4. 2
  5. ampere (A)
  6. a motor
  7. 1000
  8. 0.5
  9. 8
  10. False
  11. the flow of water
  12. True
  13. 590
  14. 1 kilowatt-hour (kWh)
  15. current
  16. 0.6
  17. 8
  18. 3
  19. True
  20. bigger
  21. anode (+)
  22. 0.3
  23. store charge briefly
  24. 10
  25. 6
  26. P = V × I
  27. saves electricity
  28. 6
  29. False
  30. 1840
  31. 4
  32. I = V ÷ R
  33. 8
  34. 235
  35. False
  36. 2.4
  37. 0.5
  38. leave the TV on standby
  39. 4
  40. 0.1

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