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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 774 · 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.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
  2. 2.🧩 A capacitor in a circuit can … (a) measure heat (b) store charge briefly (c) make light (d) spin a wheel
  3. 3.🧮 Four equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  4. 4.🔺 A current of 20 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  5. 5.🧮 A 20 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  6. 6.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  7. 7.🔍 Which is the odd one out? (a) use old filament bulbs (b) leave the TV on standby (c) iron one shirt at a time (d) use LED lamps
  8. 8.Which of these is measured in volts (V)? (a) the flow of charge (b) power (c) voltage (d) resistance
  9. 9.🔺 In the V-I-R triangle, how do we find V? (a) V = I × R (b) V = R ÷ I (c) V = I + R (d) V = I ÷ R
  10. 10.🌈 In the resistor colour code, which number does brown stand for?
  11. 11.⚡ A 9 W device works on 9 V. What current does it take (in amperes)? =
  12. 12.🔺 A 10 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
  13. 13.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
  14. 14.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) stays the same (c) gets bigger (d) gets smaller
  15. 15.💡 An LED is joined to a 5 V battery through a 330 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) lights up (b) may burn out (c) does not light
  16. 16.🧮 A 330 Ω resistor is joined in series with two equal 50 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  17. 17.🧮 A 7 V battery is joined to 4 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
  18. 18.🔺 A 4 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  19. 19.🧾 A 50 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
  20. 20.📏 Which unit measures voltage? (a) watt (W) (b) ohm (Ω) (c) ampere (A) (d) volt (V)
  21. 21.🔍 Which is the odd one out? (a) leave the TV on standby (b) iron one shirt at a time (c) use daylight to read (d) leave fridge door open
  22. 22.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
  23. 23.Which of these is measured in amperes (A)? (a) voltage (b) the flow of charge (c) energy used each second (d) resistance
  24. 24.🌈 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
  25. 25.🧮 A 220 Ω resistor is joined in series with two equal 100 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  26. 26.True or false: to use LED lamps saves electricity. (a) True (b) False
  27. 27.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 50 % (c) 25 % (d) 5 %
  28. 28.💡 Does it save or waste electricity to use old filament bulbs? (a) saves electricity (b) wastes electricity
  29. 29.🌈 In the resistor colour code, which number does grey stand for?
  30. 30.🔺 A current of 20 mA flows when 6.6 V is joined across a resistor. What is its resistance (in ohms)?
  31. 31.🧮 Three equal 30 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  32. 32.🔺 In the V-I-R triangle, how do we find R? (a) R = V ÷ I (b) R = V + I (c) R = I ÷ V (d) R = V × I
  33. 33.🌈 A resistor has the colour bands white, yellow, yellow. What is its value in kilo-ohms (kΩ)? =
  34. 34.🔍 Which is the odd one out? (a) leave the TV on standby (b) iron one shirt at a time (c) unplug idle chargers (d) run fans in empty rooms
  35. 35.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V ÷ I (c) P = V + I (d) P = V × I
  36. 36.True or false: a resistor has coloured bands. (a) False (b) True
  37. 37.💡 Does it save or waste electricity to run fans in empty rooms? (a) saves electricity (b) wastes electricity
  38. 38.🌈 A resistor has the colour bands white, violet, red. What is its value in kilo-ohms (kΩ)? =
  39. 39.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) smaller (c) stay the same (d) zero
  40. 40.🔺 A 6 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?

Answer key

  1. False
  2. store charge briefly
  3. 5
  4. 9.4
  5. 25
  6. 235
  7. use LED lamps
  8. voltage
  9. V = I × R
  10. 1
  11. 1
  12. 40
  13. 120
  14. gets smaller
  15. does not light
  16. 355
  17. 1
  18. 0.5
  19. 0.2
  20. volt (V)
  21. use daylight to read
  22. 240
  23. the flow of charge
  24. the one nearest an end
  25. 270
  26. True
  27. 5 %
  28. wastes electricity
  29. 8
  30. 330
  31. 10
  32. R = V ÷ I
  33. 940
  34. unplug idle chargers
  35. P = V × I
  36. True
  37. wastes electricity
  38. 9.7
  39. bigger
  40. 50

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