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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 736 · 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.⚡ Power tells us … (a) the colour of light (b) energy used each second (c) the size of a cell (d) the length of a wire
  2. 2.🧩 Which part changes electrical energy into movement? (a) a fuse (b) a resistor (c) a motor (d) an LED
  3. 3.🔺 A current of 25 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  4. 4.🧾 A 1500 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
  5. 5.True or false: voltage is measured in amperes (A). (a) False (b) True
  6. 6.🔺 A current of 1.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  7. 7.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a capacitor (c) a diode (d) a buzzer
  8. 8.🔺 A current of 2 A flows when 8 V is joined across a resistor. What is its resistance (in ohms)?
  9. 9.🌈 Which band is read first on a resistor? (a) the widest gap (b) any band (c) the gold band (d) the one nearest an end
  10. 10.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 4 V supply. What current flows (in mA)?
  11. 11.📏 How many kilowatts (kW) is 3650 W? =
  12. 12.🧾 A 1500 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
  13. 13.📏 Which unit measures current? (a) ampere (A) (b) ohm (Ω) (c) watt (W) (d) volt (V)
  14. 14.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 4 hours. How many watt-hours (Wh) are saved?
  15. 15.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  16. 16.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it lights brighter (c) it changes colour (d) it does not light
  17. 17.📏 Which unit measures energy used each second? (a) ampere (A) (b) ohm (Ω) (c) watt (W) (d) volt (V)
  18. 18.💡 What does LED stand for? (a) large electric dial (b) light energy dial (c) low energy device (d) light-emitting diode
  19. 19.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
  20. 20.True or false: to iron one shirt at a time wastes electricity. (a) True (b) False
  21. 21.🧩 Which component smooths a wobbly supply? (a) buzzer (b) capacitor (c) diode (d) motor
  22. 22.🔺 A current of 10 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  23. 23.🌈 A resistor has the colour bands grey, red, red. What is its value in kilo-ohms (kΩ)? =
  24. 24.⚡ A device works on 1.5 V and takes 2 A. What is its power (in watts)? =
  25. 25.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 ampere (c) 1 kilowatt-hour (kWh) (d) 1 watt
  26. 26.🔺 A current of 0.1 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  27. 27.🔺 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
  28. 28.⚡ A 2.5 W device works on 5 V. What current does it take (in amperes)? =
  29. 29.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  30. 30.💡 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?
  31. 31.🧩 Which component lets current go one way? (a) buzzer (b) transistor (c) diode (d) fuse
  32. 32.⚡ Which formula gives electric power? (a) P = V + I (b) P = V × I (c) P = I ÷ V (d) P = V ÷ I
  33. 33.⚡ A device works on 3 V and takes 0.5 A. What is its power (in watts)? =
  34. 34.🧩 Which component senses how hot it is? (a) capacitor (b) resistor (c) thermistor (d) fuse
  35. 35.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) bigger (c) stay the same (d) zero
  36. 36.⚡ A device works on 24 V and takes 2 A. What is its power (in watts)? =
  37. 37.💡 Does it save or waste electricity to set the AC to 24 °C? (a) saves electricity (b) wastes electricity
  38. 38.⚡ A device works on 5 V and takes 0.25 A. What is its power (in watts)? =
  39. 39.True or false: the ammeter measures current. (a) True (b) False
  40. 40.🔺 A current of 50 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =

Answer key

  1. energy used each second
  2. a motor
  3. 3.75
  4. 6
  5. False
  6. 30
  7. a buzzer
  8. 4
  9. the one nearest an end
  10. 10
  11. 3.65
  12. 12
  13. ampere (A)
  14. 136
  15. anode (+)
  16. it does not light
  17. watt (W)
  18. light-emitting diode
  19. voltmeter
  20. True
  21. capacitor
  22. 200
  23. 8.2
  24. 3
  25. 1 kilowatt-hour (kWh)
  26. 1.5
  27. R = V ÷ I
  28. 0.5
  29. cathode (−)
  30. 300
  31. diode
  32. P = V × I
  33. 1.5
  34. thermistor
  35. bigger
  36. 48
  37. saves electricity
  38. 1.25
  39. True
  40. 16.5

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