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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 636 · 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 resistor has the colour bands green, black, red. What is its value (in ohms)?
  2. 2.🌈 A resistor has the colour bands blue, blue, red. What is its value in kilo-ohms (kΩ)? =
  3. 3.Which of these is measured in amperes (A)? (a) the push of a cell (b) the flow of charge (c) resistance (d) voltage
  4. 4.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it changes colour (c) it does not light (d) it lights brighter
  5. 5.True or false: on an LED, the round-side leg is the anode (+). (a) True (b) False
  6. 6.💡 An LED is joined to a 6 V battery through a 1000 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) does not light (b) lights up (c) may burn out
  7. 7.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
  8. 8.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) stays the same (c) becomes zero (d) gets smaller
  9. 9.⚡ A device works on 12 V and takes 0.5 A. What is its power (in watts)? =
  10. 10.True or false: to switch off empty rooms wastes electricity. (a) True (b) False
  11. 11.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 ampere (c) 1 kilowatt-hour (kWh) (d) 1 volt
  12. 12.🌈 A resistor has the colour bands white, green, brown. What is its value (in ohms)?
  13. 13.📏 How many kilowatts (kW) is 4400 W? =
  14. 14.🌈 In the resistor colour code, which number does blue stand for?
  15. 15.🔺 A 4 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
  16. 16.True or false: the ammeter is joined in series. (a) True (b) False
  17. 17.💡 What does LED stand for? (a) light-emitting diode (b) low energy device (c) large electric dial (d) light energy dial
  18. 18.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V × I (c) P = V + I (d) P = V ÷ I
  19. 19.🌈 A resistor has the colour bands green, red, orange. What is its value (in ohms)?
  20. 20.🔺 A current of 0.25 A flows when 1.25 V is joined across a resistor. What is its resistance (in ohms)?
  21. 21.🧮 Five equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  22. 22.📏 How many milliamperes (mA) is 1.78 A?
  23. 23.True or false: to iron one shirt at a time wastes electricity. (a) False (b) True
  24. 24.🔺 A 3.75 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  25. 25.🧮 Three equal 15 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  26. 26.Which of these is measured in volts (V)? (a) power (b) resistance (c) energy used each second (d) voltage
  27. 27.📏 How many milliamperes (mA) make 1 ampere? (a) 10 (b) 100 (c) 1000 (d) 60
  28. 28.🔺 A current of 2.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  29. 29.True or false: to use LED lamps saves electricity. (a) False (b) True
  30. 30.Which of these is measured in ohms (Ω)? (a) resistance (b) current (c) energy used each second (d) the push of a cell
  31. 31.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a capacitor (c) a diode (d) a buzzer
  32. 32.🔺 A current of 0.25 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  33. 33.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  34. 34.🧮 Two resistors in parallel give a total that is … (a) their sum (b) less than either one (c) more than either one (d) always zero
  35. 35.🧮 Resistors of 68 Ω, 50 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
  36. 36.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = I ÷ V (c) R = V + I (d) R = V ÷ I
  37. 37.🔺 A 23.5 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  38. 38.True or false: to switch off empty rooms saves electricity. (a) True (b) False
  39. 39.🌈 In the resistor colour code, which number does yellow stand for?
  40. 40.📏 Which unit measures current? (a) ampere (A) (b) watt (W) (c) ohm (Ω) (d) volt (V)

Answer key

  1. 5000
  2. 6.6
  3. the flow of charge
  4. it does not light
  5. True
  6. does not light
  7. False
  8. gets smaller
  9. 6
  10. False
  11. 1 kilowatt-hour (kWh)
  12. 950
  13. 4.4
  14. 6
  15. 20
  16. True
  17. light-emitting diode
  18. P = V × I
  19. 52000
  20. 5
  21. 10
  22. 1780
  23. True
  24. 25
  25. 5
  26. voltage
  27. 1000
  28. 12.5
  29. True
  30. resistance
  31. a buzzer
  32. 8
  33. cathode (−)
  34. less than either one
  35. 138
  36. R = V ÷ I
  37. 50
  38. True
  39. 4
  40. ampere (A)

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