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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 770 · 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 leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  2. 2.⚡ Which formula gives electric power? (a) P = V × I (b) P = V ÷ I (c) P = I ÷ V (d) P = V + I
  3. 3.🔺 A current of 20 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  4. 4.🔺 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
  5. 5.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 8000 Ω resistor? (a) grey-black-brown (b) grey-black-red (c) grey-black-orange (d) white-grey-red
  6. 6.What does an LDR do? (a) has coloured bands (b) is a resistance knob (c) boosts a small signal (d) senses how bright it is
  7. 7.🔺 A current of 2.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  8. 8.🧩 Which component beeps for an alarm? (a) LED (b) thermistor (c) resistor (d) buzzer
  9. 9.🔺 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
  10. 10.🌈 A resistor has the colour bands yellow, orange, red. What is its value (in ohms)?
  11. 11.🔺 A current of 3 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  12. 12.🔺 A current of 40 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  13. 13.Which of these is measured in volts (V)? (a) the flow of charge (b) how much a part resists (c) energy used each second (d) voltage
  14. 14.🔺 A 36 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  15. 15.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
  16. 16.🧮 Four equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  17. 17.⚡ A device works on 24 V and takes 0.2 A. What is its power (in watts)? =
  18. 18.🔺 A current of 40 mA flows when 16 V is joined across a resistor. What is its resistance (in ohms)?
  19. 19.Which of these is measured in ohms (Ω)? (a) the push of a cell (b) resistance (c) energy used each second (d) power
  20. 20.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  21. 21.🔺 A current of 3 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  22. 22.Which of these saves electricity? (a) set the AC to 24 °C (b) leave the TV on standby (c) leave fridge door open (d) use old filament bulbs
  23. 23.🧾 Which lamp gives the same light for the least power? (a) a candle (b) a filament bulb (c) an LED lamp (d) an oil lamp
  24. 24.📏 How many kilowatts (kW) is 2200 W? =
  25. 25.🧩 Which part changes electrical energy into sound? (a) a buzzer (b) a capacitor (c) a diode (d) a resistor
  26. 26.💡 Does it save or waste electricity to use old filament bulbs? (a) saves electricity (b) wastes electricity
  27. 27.Which of these saves electricity? (a) use old filament bulbs (b) iron one shirt at a time (c) leave fridge door open (d) unplug idle chargers
  28. 28.🧩 Which part changes electrical energy into movement? (a) a fuse (b) an LED (c) a motor (d) a resistor
  29. 29.🔺 A current of 0.25 A flows when 0.75 V is joined across a resistor. What is its resistance (in ohms)?
  30. 30.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
  31. 31.🌈 A resistor has the colour bands green, red, black. What is its value (in ohms)?
  32. 32.🧮 Two resistors in parallel give a total that is … (a) always zero (b) their sum (c) more than either one (d) less than either one
  33. 33.True or false: to switch off empty rooms wastes electricity. (a) True (b) False
  34. 34.🔺 A current of 40 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.💡 What does LED stand for? (a) large electric dial (b) light-emitting diode (c) low energy device (d) light energy dial
  36. 36.True or false: on an LED, the round-side leg is the cathode (−). (a) False (b) True
  37. 37.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 kilowatt-hour (kWh) (c) 1 volt (d) 1 ampere
  38. 38.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  39. 39.🔺 A current of 3 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  40. 40.🔺 A current of 0.2 A flows when 0.8 V is joined across a resistor. What is its resistance (in ohms)?

Answer key

  1. cathode (−)
  2. P = V × I
  3. 2
  4. V = I × R
  5. grey-black-red
  6. senses how bright it is
  7. 50
  8. buzzer
  9. R = V ÷ I
  10. 4300
  11. 12
  12. 6
  13. voltage
  14. 3
  15. voltmeter
  16. 5
  17. 4.8
  18. 400
  19. resistance
  20. 10
  21. 60
  22. set the AC to 24 °C
  23. an LED lamp
  24. 2.2
  25. a buzzer
  26. wastes electricity
  27. unplug idle chargers
  28. a motor
  29. 3
  30. True
  31. 52
  32. less than either one
  33. False
  34. 20
  35. light-emitting diode
  36. False
  37. 1 kilowatt-hour (kWh)
  38. 165
  39. 24
  40. 4

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