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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 12 · 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 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 9 hours. How many watt-hours (Wh) are saved?
  2. 2.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
  3. 3.🔺 A 7.5 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  4. 4.🧮 Five equal 25 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  5. 5.🔺 A current of 0.2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.⚡ A device works on 24 V and takes 1.5 A. What is its power (in watts)? =
  7. 7.🧮 Two resistors in parallel give a total that is … (a) their sum (b) less than either one (c) always zero (d) more than either one
  8. 8.🧾 A 2000 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
  9. 9.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = V × I (d) P = I ÷ V
  10. 10.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) bigger (c) zero (d) stay the same
  11. 11.🧮 Resistors of 100 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
  12. 12.🔺 A current of 1.5 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  13. 13.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  14. 14.🌈 In the resistor colour code, which number does red stand for?
  15. 15.🧮 Resistors of 100 Ω and 100 Ω are joined in series. What is the total resistance (in ohms)?
  16. 16.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  17. 17.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
  18. 18.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to limit the current (c) to store charge (d) to change its colour
  19. 19.🔺 A 0.3 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  20. 20.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  21. 21.🌈 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
  22. 22.🧩 Which part changes electrical energy into movement? (a) a motor (b) a fuse (c) an LED (d) a resistor
  23. 23.💡 Does it save or waste electricity to leave the TV on standby? (a) wastes electricity (b) saves electricity
  24. 24.🔺 A current of 2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.Which of these is measured in volts (V)? (a) energy used each second (b) the push of a cell (c) the flow of charge (d) how much a part resists
  26. 26.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 10 hours. How many watt-hours (Wh) are saved?
  27. 27.🔺 A current of 0.1 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  28. 28.🔺 A current of 0.5 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  29. 29.True or false: a motor lets current go one way. (a) True (b) False
  30. 30.📏 Which unit measures the push of a cell? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
  31. 31.🔺 A current of 2.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  32. 32.🧮 A 3.25 V battery is joined to 10 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
  33. 33.⚡ A device works on 24 V and takes 3 A. What is its power (in watts)? =
  34. 34.🧮 Three equal 30 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  35. 35.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 840 Ω resistor? (a) grey-yellow-red (b) grey-yellow-brown (c) yellow-grey-brown (d) grey-yellow-black
  36. 36.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 5 hours. How many watt-hours (Wh) are saved?
  37. 37.🔺 A current of 20 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  38. 38.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets bigger (c) becomes zero (d) gets smaller
  39. 39.🔺 A current of 2 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  40. 40.🔍 Which is the odd one out? (a) use daylight to read (b) use LED lamps (c) unplug idle chargers (d) leave the TV on standby

Answer key

  1. 765
  2. 460
  3. 1.5
  4. 5
  5. 0.6
  6. 36
  7. less than either one
  8. 20
  9. P = V × I
  10. bigger
  11. 120
  12. 22.5
  13. anode (+)
  14. 2
  15. 200
  16. 5
  17. voltmeter
  18. to limit the current
  19. 0.1
  20. cathode (−)
  21. the one nearest an end
  22. a motor
  23. wastes electricity
  24. 20
  25. the push of a cell
  26. 510
  27. 0.8
  28. 12
  29. False
  30. volt (V)
  31. 5
  32. 0.25
  33. 72
  34. 10
  35. grey-yellow-brown
  36. 425
  37. 2.4
  38. gets smaller
  39. 3
  40. leave the TV on standby

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