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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 842 · 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 250 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
  2. 2.🧮 A 50 Ω resistor is joined in series with two equal 470 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  3. 3.🧮 Resistors of 68 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
  4. 4.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 volt (c) 1 kilowatt-hour (kWh) (d) 1 ampere
  5. 5.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  6. 6.⚡ Power tells us … (a) the colour of light (b) the size of a cell (c) the length of a wire (d) energy used each second
  7. 7.🧮 Five equal 25 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  8. 8.🔺 A current of 25 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  9. 9.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  10. 10.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 530 Ω resistor? (a) green-orange-red (b) orange-green-brown (c) green-orange-brown (d) green-orange-black
  11. 11.True or false: a capacitor stores a little charge. (a) False (b) True
  12. 12.🧮 A 4 V battery is joined to 10 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
  13. 13.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 100 (b) 1024 (c) 1000 (d) 10
  14. 14.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) zero (c) bigger (d) stay the same
  15. 15.💡 Does it save or waste electricity to switch off empty rooms? (a) saves electricity (b) wastes electricity
  16. 16.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
  17. 17.⚡ A 24 W device works on 12 V. What current does it take (in amperes)? =
  18. 18.🔺 A current of 2.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  19. 19.📏 How many kilo-ohms (kΩ) is 9800 Ω? =
  20. 20.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a buzzer (c) a diode (d) a capacitor
  21. 21.🔺 A current of 50 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  22. 22.🔺 A 1.25 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  23. 23.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
  24. 24.💡 Does it save or waste electricity to close the fridge quickly? (a) wastes electricity (b) saves electricity
  25. 25.⚡ A device works on 3 V and takes 0.2 A. What is its power (in watts)? =
  26. 26.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 0 % (d) 5 %
  27. 27.📏 Which unit measures energy used each second? (a) ampere (A) (b) volt (V) (c) ohm (Ω) (d) watt (W)
  28. 28.Which of these wastes electricity? (a) set the AC to 24 °C (b) close the fridge quickly (c) use LED lamps (d) leave the TV on standby
  29. 29.🧮 A 4.25 V battery is joined to 12 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
  30. 30.Which of these saves electricity? (a) leave the TV on standby (b) run fans in empty rooms (c) unplug idle chargers (d) leave fridge door open
  31. 31.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
  32. 32.⚡ A 13.5 W device works on 9 V. What current does it take (in amperes)? =
  33. 33.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
  34. 34.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
  35. 35.📏 How many amperes (A) is 2020 mA? =
  36. 36.⚡ A device works on 1.5 V and takes 0.2 A. What is its power (in watts)? =
  37. 37.🧩 Which component makes a beeping sound? (a) motor (b) diode (c) transistor (d) buzzer
  38. 38.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) more than either one (c) always zero (d) their sum
  39. 39.🌈 A resistor has the colour bands brown, grey, brown. What is its value (in ohms)?
  40. 40.🧮 A 50 Ω resistor is joined in series with two equal 220 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?

Answer key

  1. 0.5
  2. 285
  3. 78
  4. 1 kilowatt-hour (kWh)
  5. anode (+)
  6. energy used each second
  7. 5
  8. 11.75
  9. 345
  10. green-orange-brown
  11. True
  12. 0.2
  13. 1000
  14. bigger
  15. saves electricity
  16. 460
  17. 2
  18. 12.5
  19. 9.8
  20. a buzzer
  21. 12.5
  22. 0.25
  23. False
  24. saves electricity
  25. 0.6
  26. 5 %
  27. watt (W)
  28. leave the TV on standby
  29. 0.25
  30. unplug idle chargers
  31. 920
  32. 1.5
  33. ammeter
  34. False
  35. 2.02
  36. 0.3
  37. buzzer
  38. less than either one
  39. 180
  40. 160

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