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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 375 · 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 current of 0.1 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  2. 2.🔺 A 3 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  3. 3.True or false: to use LED lamps saves electricity. (a) False (b) True
  4. 4.🔺 A current of 0.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  5. 5.📏 How many amperes (A) is 1100 mA? =
  6. 6.🔺 A 30 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  7. 7.🧩 A capacitor in a circuit can … (a) spin a wheel (b) store charge briefly (c) measure heat (d) make light
  8. 8.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) zero (c) smaller (d) bigger
  9. 9.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) an LED lamp (c) a candle (d) an oil lamp
  10. 10.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 2 hours. How many watt-hours (Wh) are saved?
  11. 11.💡 A red LED uses 2 V and should get 25 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
  12. 12.🌈 A resistor has the colour bands brown, black, red. What is its value (in ohms)?
  13. 13.🧮 Three equal 30 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  14. 14.🔺 A current of 1 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.🌈 In the resistor colour code, which number does brown stand for?
  16. 16.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 9 hours. How many watt-hours (Wh) are saved?
  17. 17.True or false: a resistor lets current go one way. (a) False (b) True
  18. 18.🔺 An 8 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  19. 19.📏 Which unit measures how much a part resists? (a) ohm (Ω) (b) watt (W) (c) ampere (A) (d) volt (V)
  20. 20.🔺 A current of 40 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  21. 21.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it does not light (c) it lights brighter (d) it changes colour
  22. 22.🔺 A current of 2.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.🌈 Which band is read first on a resistor? (a) any band (b) the one nearest an end (c) the gold band (d) the widest gap
  24. 24.Which of these saves electricity? (a) leave the TV on standby (b) run fans in empty rooms (c) use LED lamps (d) leave fridge door open
  25. 25.🔺 A current of 20 mA flows when 6.6 V is joined across a resistor. What is its resistance (in ohms)?
  26. 26.🧩 Which part changes electrical energy into movement? (a) an LED (b) a resistor (c) a fuse (d) a motor
  27. 27.🧮 Two resistors in parallel give a total that is … (a) always zero (b) their sum (c) less than either one (d) more than either one
  28. 28.True or false: on an LED, the leg by the flat edge is the anode (+). (a) True (b) False
  29. 29.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 13 Ω resistor? (a) red-orange-black (b) brown-orange-black (c) brown-orange-brown (d) orange-brown-black
  30. 30.Which of these wastes electricity? (a) close the fridge quickly (b) use daylight to read (c) use old filament bulbs (d) switch off empty rooms
  31. 31.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 33000 Ω resistor? (a) orange-orange-yellow (b) orange-orange-red (c) orange-orange-orange (d) orange-yellow-orange
  32. 32.🔺 A current of 2.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  33. 33.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 3 hours. How many watt-hours (Wh) are saved?
  34. 34.🔺 A current of 50 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.🔺 A current of 50 mA flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  36. 36.🔺 A current of 0.2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  37. 37.🧮 A 22 Ω resistor is joined in series with two equal 220 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  38. 38.🔺 A 36 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  39. 39.📏 Which unit measures power? (a) volt (V) (b) ohm (Ω) (c) ampere (A) (d) watt (W)
  40. 40.🔍 Which is the odd one out? (a) switch off empty rooms (b) use daylight to read (c) leave fridge door open (d) use LED lamps

Answer key

  1. 0.6
  2. 25
  3. True
  4. 6
  5. 1.1
  6. 2
  7. store charge briefly
  8. bigger
  9. an LED lamp
  10. 102
  11. 160
  12. 1000
  13. 10
  14. 4
  15. 1
  16. 459
  17. False
  18. 2
  19. ohm (Ω)
  20. 20
  21. it does not light
  22. 20
  23. the one nearest an end
  24. use LED lamps
  25. 330
  26. a motor
  27. less than either one
  28. False
  29. brown-orange-black
  30. use old filament bulbs
  31. orange-orange-orange
  32. 10
  33. 189
  34. 6
  35. 120
  36. 0.8
  37. 132
  38. 3
  39. watt (W)
  40. leave fridge door open

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