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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 97 · 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 330 Ω resistor is joined in series with two equal 330 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  2. 2.🔺 A current of 1.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  3. 3.🧩 A capacitor in a circuit can … (a) measure heat (b) spin a wheel (c) store charge briefly (d) make light
  4. 4.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
  5. 5.🧮 Resistors of 220 Ω, 220 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
  6. 6.⚡ A 6 W device works on 24 V. What current does it take (in amperes)? =
  7. 7.🌈 In the resistor colour code, which number does green stand for?
  8. 8.🔺 A current of 50 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  9. 9.True or false: a capacitor stores a little charge. (a) False (b) True
  10. 10.⚡ A device works on 9 V and takes 3 A. What is its power (in watts)? =
  11. 11.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 41 Ω resistor? (a) brown-yellow-black (b) yellow-brown-brown (c) green-brown-black (d) yellow-brown-black
  12. 12.🔺 A current of 0.25 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  13. 13.🧮 Resistors of 33 Ω and 220 Ω are joined in series. What is the total resistance (in ohms)?
  14. 14.What does a motor do? (a) turns a fan or wheels (b) stores a little charge (c) senses how bright it is (d) has coloured bands
  15. 15.🧮 A 470 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)?
  16. 16.🔺 A 4.8 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  17. 17.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  18. 18.🔺 A current of 10 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  19. 19.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.Which of these is measured in ohms (Ω)? (a) power (b) the flow of charge (c) resistance (d) current
  21. 21.🧮 Resistors of 20 Ω, 47 Ω, 22 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
  22. 22.🔺 A current of 3 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
  24. 24.💡 Does it save or waste electricity to use old filament bulbs? (a) saves electricity (b) wastes electricity
  25. 25.🧮 A 33 Ω resistor is joined in series with two equal 200 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  26. 26.Which of these wastes electricity? (a) use LED lamps (b) unplug idle chargers (c) close the fridge quickly (d) leave fridge door open
  27. 27.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) zero (c) stay the same (d) smaller
  28. 28.🔺 A 10 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  29. 29.📏 Which unit measures energy used each second? (a) ohm (Ω) (b) ampere (A) (c) volt (V) (d) watt (W)
  30. 30.🔺 A current of 2.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
  32. 32.What does a diode do? (a) senses how bright it is (b) stores a little charge (c) senses how hot it is (d) lets current go one way
  33. 33.🔺 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
  34. 34.🧾 A family uses 20 units of electricity in a month and each unit costs ₹8. What is the bill (in ₹)?
  35. 35.🔺 A current of 2 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = I ÷ V (d) P = V × I
  37. 37.💡 A red LED uses 2 V and should get 25 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  38. 38.💡 An LED is joined to a 12 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) lights up (b) does not light (c) may burn out
  39. 39.Which of these saves electricity? (a) leave fridge door open (b) run fans in empty rooms (c) switch off empty rooms (d) iron one shirt at a time
  40. 40.True or false: a thermistor lets current go one way. (a) False (b) True

Answer key

  1. 495
  2. 12
  3. store charge briefly
  4. 300
  5. 910
  6. 0.25
  7. 5
  8. 23.5
  9. True
  10. 27
  11. yellow-brown-black
  12. 0.75
  13. 253
  14. turns a fan or wheels
  15. 520
  16. 40
  17. anode (+)
  18. 4
  19. 1.2
  20. resistance
  21. 157
  22. 45
  23. True
  24. wastes electricity
  25. 133
  26. leave fridge door open
  27. bigger
  28. 0.5
  29. watt (W)
  30. 30
  31. 1840
  32. lets current go one way
  33. V = I × R
  34. 160
  35. 10
  36. P = V × I
  37. 120
  38. may burn out
  39. switch off empty rooms
  40. False

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