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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 292 · 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.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  2. 2.🔺 An 8 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  3. 3.⚡ A 3 W device works on 6 V. What current does it take (in amperes)? =
  4. 4.🌈 A resistor has the colour bands blue, brown, orange. What is its value (in ohms)?
  5. 5.⚡ A device works on 6 V and takes 1 A. What is its power (in watts)? =
  6. 6.🔍 Which is the odd one out? (a) run fans in empty rooms (b) unplug idle chargers (c) switch off empty rooms (d) use daylight to read
  7. 7.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
  8. 8.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) bigger (c) smaller (d) stay the same
  9. 9.🧮 Resistors of 10 Ω, 22 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
  10. 10.🔺 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
  11. 11.What does a resistor do? (a) limits the current (b) stores a little charge (c) turns a fan or wheels (d) blows if current is high
  12. 12.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
  13. 13.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 5 % (c) 50 % (d) 0 %
  14. 14.🔺 A current of 2 A flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  15. 15.True or false: current is measured in volts (V). (a) False (b) True
  16. 16.🔺 A current of 10 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.🧾 A 2000 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
  18. 18.📏 Which unit measures the flow of charge? (a) ampere (A) (b) watt (W) (c) ohm (Ω) (d) volt (V)
  19. 19.True or false: to leave the TV on standby wastes electricity. (a) True (b) False
  20. 20.⚡ A 27 W device works on 9 V. What current does it take (in amperes)? =
  21. 21.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = V ÷ R (c) I = R ÷ V (d) I = V × R
  22. 22.🔺 A current of 40 mA flows when 18.8 V is joined across a resistor. What is its resistance (in ohms)?
  23. 23.🔺 A current of 0.2 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  24. 24.🔺 A current of 2.5 A flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  25. 25.🧮 Resistors of 10 Ω, 150 Ω and 100 Ω are joined in series. What is the total resistance (in ohms)?
  26. 26.⚡ A 0.375 W device works on 1.5 V. What current does it take (in amperes)? =
  27. 27.🧮 Four equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  28. 28.🔺 A 1.2 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  29. 29.⚡ Power tells us … (a) the size of a cell (b) energy used each second (c) the colour of light (d) the length of a wire
  30. 30.🔺 A current of 40 mA flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  31. 31.What does a fuse do? (a) blows if current is high (b) is a resistance knob (c) lets current go one way (d) beeps for an alarm
  32. 32.What does a resistor do? (a) is a resistance knob (b) senses how bright it is (c) smooths a wobbly supply (d) has coloured bands
  33. 33.🔺 A 12 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  34. 34.🧩 Which component boosts a small signal? (a) transistor (b) buzzer (c) potentiometer (d) diode
  35. 35.🌈 A resistor has the colour bands brown, yellow, orange. What is its value (in ohms)?
  36. 36.📏 In the water-pipe picture of a circuit, resistance is like … (a) the flow of water (b) the water pressure (c) a narrow pipe (d) a bigger tank
  37. 37.💡 Does it save or waste electricity to use LED lamps? (a) wastes electricity (b) saves electricity
  38. 38.🌈 A resistor has the colour bands blue, violet, black. What is its value (in ohms)?
  39. 39.True or false: to use old filament bulbs saves electricity. (a) True (b) False
  40. 40.🔺 A current of 40 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =

Answer key

  1. cathode (−)
  2. 2
  3. 0.5
  4. 61000
  5. 6
  6. run fans in empty rooms
  7. 920
  8. bigger
  9. 65
  10. V = I × R
  11. limits the current
  12. 460
  13. 5 %
  14. 5
  15. False
  16. 2
  17. 20
  18. ampere (A)
  19. True
  20. 3
  21. I = V ÷ R
  22. 470
  23. 1.2
  24. 4
  25. 260
  26. 0.25
  27. 5
  28. 10
  29. energy used each second
  30. 150
  31. blows if current is high
  32. has coloured bands
  33. 2
  34. transistor
  35. 14000
  36. a narrow pipe
  37. saves electricity
  38. 67
  39. False
  40. 8

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