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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 61 · 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.

NameDateTime takenScore ___ / 40
  1. 1.True or false: resistance is measured in ohms (Ω). (a) True (b) False
  2. 2.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I + R (c) V = I × R (d) V = I ÷ R
  3. 3.🔺 A current of 2.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  4. 4.🔺 A 0.75 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  5. 5.True or false: on an LED, the longer leg is the anode (+). (a) False (b) True
  6. 6.🔺 A current of 10 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  7. 7.🧮 A 2 V battery is joined to 3 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
  8. 8.📏 How many watts (W) is 0.1 kW?
  9. 9.📏 Which unit measures current? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
  10. 10.🧩 Which component senses how hot it is? (a) fuse (b) LED (c) buzzer (d) thermistor
  11. 11.🧾 A 1000 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
  12. 12.⚡ A device works on 1.5 V and takes 0.2 A. What is its power (in watts)? =
  13. 13.⚡ Power tells us … (a) the size of a cell (b) the length of a wire (c) energy used each second (d) the colour of light
  14. 14.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) less than either one (c) their sum (d) always zero
  15. 15.🧮 Resistors of 68 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
  16. 16.💡 An LED is joined to a 6 V battery through a 330 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) lights up (c) may burn out
  17. 17.🔺 A current of 20 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  18. 18.🔺 A current of 40 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  19. 19.🧩 Which component has coloured bands? (a) resistor (b) capacitor (c) LDR (d) diode
  20. 20.🌈 In the resistor colour code, which number does grey stand for?
  21. 21.📏 In the water-pipe picture of a circuit, resistance is like … (a) a narrow pipe (b) the water pressure (c) the flow of water (d) a bigger tank
  22. 22.📏 In the water-pipe picture of a circuit, current is like … (a) a narrow pipe (b) the flow of water (c) the pipe colour (d) the water pressure
  23. 23.Which of these is measured in watts (W)? (a) voltage (b) how much a part resists (c) the flow of charge (d) power
  24. 24.🔺 In the V-I-R triangle, how do we find I? (a) I = V ÷ R (b) I = R ÷ V (c) I = V × R (d) I = V + R
  25. 25.True or false: to use LED lamps wastes electricity. (a) False (b) True
  26. 26.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = I ÷ V (d) P = V × I
  27. 27.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
  28. 28.🔺 A current of 50 mA flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
  29. 29.💡 Does it save or waste electricity to leave the TV on standby? (a) wastes electricity (b) saves electricity
  30. 30.🔺 A current of 2.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.🔺 A current of 40 mA flows when 13.2 V is joined across a resistor. What is its resistance (in ohms)?
  32. 32.🔺 A current of 2.5 A flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  33. 33.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 5 % (c) 25 % (d) 0 %
  34. 34.🔺 A 7.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  35. 35.🔺 A current of 50 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.📏 How many watts (W) is 2 kW?
  37. 37.🔺 A 12 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  38. 38.True or false: a motor has coloured bands. (a) True (b) False
  39. 39.🔺 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
  40. 40.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)

Answer key

  1. True
  2. V = I × R
  3. 20
  4. 0.25
  5. True
  6. 200
  7. 0.25
  8. 100
  9. ampere (A)
  10. thermistor
  11. 5
  12. 0.3
  13. energy used each second
  14. less than either one
  15. 218
  16. lights up
  17. 2.4
  18. 18.8
  19. resistor
  20. 8
  21. a narrow pipe
  22. the flow of water
  23. power
  24. I = V ÷ R
  25. False
  26. P = V × I
  27. ammeter
  28. 400
  29. wastes electricity
  30. 7.5
  31. 330
  32. 4
  33. 5 %
  34. 50
  35. 12.5
  36. 2000
  37. 1.5
  38. False
  39. R = V ÷ I
  40. cathode (−)

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