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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 719 · 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: the ammeter measures voltage. (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.🧩 Which component senses how bright it is? (a) diode (b) resistor (c) buzzer (d) LDR
  4. 4.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to limit the current (c) to store charge (d) to make it brighter
  5. 5.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V × R (c) I = V ÷ R (d) I = V + R
  6. 6.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  7. 7.🧮 Five equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  8. 8.🌈 In the resistor colour code, which number does violet stand for?
  9. 9.⚡ Which formula gives electric power? (a) P = V × I (b) P = I ÷ V (c) P = V ÷ I (d) P = V + I
  10. 10.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  11. 11.🔺 A current of 1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  12. 12.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  13. 13.True or false: on an LED, the longer leg is the anode (+). (a) False (b) True
  14. 14.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) gets bigger (c) stays the same (d) becomes zero
  15. 15.💡 Does it save or waste electricity to set the AC to 24 °C? (a) saves electricity (b) wastes electricity
  16. 16.🧩 Which part changes electrical energy into movement? (a) a fuse (b) an LED (c) a resistor (d) a motor
  17. 17.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 7 hours. How many watt-hours (Wh) are saved?
  18. 18.🌈 A resistor has the colour bands grey, black, orange. What is its value (in ohms)?
  19. 19.🌈 A resistor has the colour bands brown, green, orange. What is its value (in ohms)?
  20. 20.🔺 A current of 0.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  21. 21.🔺 A 20 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  22. 22.💡 Does it save or waste electricity to close the fridge quickly? (a) saves electricity (b) wastes electricity
  23. 23.🔺 A 15 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  24. 24.🔺 A current of 25 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.⚡ Power tells us … (a) the length of a wire (b) the size of a cell (c) the colour of light (d) energy used each second
  26. 26.🧮 Four equal 80 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  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.📏 How many kilowatts (kW) is 3450 W? =
  29. 29.🧮 Resistors of 33 Ω, 330 Ω, 330 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
  30. 30.🔺 A current of 10 mA flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
  31. 31.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
  32. 32.⚡ A 5 W device works on 5 V. What current does it take (in amperes)? =
  33. 33.🔺 A current of 1.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  34. 34.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
  35. 35.🧩 Which part changes electrical energy into sound? (a) a buzzer (b) a resistor (c) a capacitor (d) a diode
  36. 36.🔺 A 12 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  37. 37.🔺 A current of 25 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  38. 38.🔍 Which is the odd one out? (a) use LED lamps (b) switch off empty rooms (c) set the AC to 24 °C (d) use old filament bulbs
  39. 39.🌈 In the resistor colour code, which number does white stand for?
  40. 40.🧾 A 200 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =

Answer key

  1. False
  2. V = I × R
  3. LDR
  4. to limit the current
  5. I = V ÷ R
  6. anode (+)
  7. 20
  8. 7
  9. P = V × I
  10. cathode (−)
  11. 2
  12. cathode (−)
  13. True
  14. gets smaller
  15. saves electricity
  16. a motor
  17. 595
  18. 80000
  19. 15000
  20. 1
  21. 1
  22. saves electricity
  23. 3
  24. 8.25
  25. energy used each second
  26. 20
  27. R = V ÷ I
  28. 3.45
  29. 715
  30. 120
  31. ammeter
  32. 1
  33. 18
  34. False
  35. a buzzer
  36. 3
  37. 5
  38. use old filament bulbs
  39. 9
  40. 0.8

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