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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 333 · 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.📏 How many kilo-ohms (kΩ) is 8900 Ω? =
  2. 2.🧩 Which component smooths a wobbly supply? (a) LDR (b) capacitor (c) diode (d) LED
  3. 3.Which of these wastes electricity? (a) use daylight to read (b) set the AC to 24 °C (c) switch off empty rooms (d) use old filament bulbs
  4. 4.🔺 A 10 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  5. 5.🔺 A 20 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  6. 6.🔺 A current of 50 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  7. 7.⚡ Power tells us … (a) the length of a wire (b) the colour of light (c) the size of a cell (d) energy used each second
  8. 8.🌈 A resistor has the colour bands yellow, brown, black. What is its value (in ohms)?
  9. 9.🔺 A current of 20 mA flows when 2.4 V is joined across a resistor. What is its resistance (in ohms)?
  10. 10.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 kilowatt-hour (kWh) (c) 1 watt (d) 1 volt
  11. 11.🔺 A current of 20 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  12. 12.🧮 Three equal 30 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  13. 13.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.🧩 Which part changes electrical energy into movement? (a) a motor (b) an LED (c) a resistor (d) a fuse
  15. 15.🔺 A current of 10 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  16. 16.🧾 A 1500 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
  17. 17.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) becomes zero (c) gets smaller (d) gets bigger
  18. 18.True or false: the ammeter measures voltage. (a) True (b) False
  19. 19.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a buzzer (c) a capacitor (d) a diode
  20. 20.🔺 A current of 1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  21. 21.Which of these wastes electricity? (a) run fans in empty rooms (b) use LED lamps (c) switch off empty rooms (d) use daylight to read
  22. 22.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 1 hour. How many watt-hours (Wh) are saved?
  23. 23.🌈 A resistor has the colour bands green, red, yellow. What is its value in kilo-ohms (kΩ)? =
  24. 24.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
  25. 25.🔺 A current of 0.25 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  26. 26.⚡ A 1.2 W device works on 12 V. What current does it take (in amperes)? =
  27. 27.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 4 V supply. What current flows (in mA)?
  28. 28.📏 Which unit measures power? (a) ohm (Ω) (b) watt (W) (c) volt (V) (d) ampere (A)
  29. 29.Which of these is measured in watts (W)? (a) resistance (b) energy used each second (c) the flow of charge (d) how much a part resists
  30. 30.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  31. 31.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
  32. 32.🧮 Resistors of 100 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
  33. 33.⚡ A device works on 5 V and takes 3 A. What is its power (in watts)? =
  34. 34.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 510 Ω resistor? (a) green-brown-red (b) green-brown-black (c) brown-green-brown (d) green-brown-brown
  35. 35.⚡ Which formula gives electric power? (a) P = V × I (b) P = V + I (c) P = I ÷ V (d) P = V ÷ I
  36. 36.Which of these is measured in volts (V)? (a) the push of a cell (b) current (c) resistance (d) the flow of charge
  37. 37.True or false: to use LED lamps wastes electricity. (a) False (b) True
  38. 38.Which of these wastes electricity? (a) use LED lamps (b) switch off empty rooms (c) leave the TV on standby (d) close the fridge quickly
  39. 39.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 9 hours. How many watt-hours (Wh) are saved?
  40. 40.🔺 A 25 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?

Answer key

  1. 8.9
  2. capacitor
  3. use old filament bulbs
  4. 25
  5. 50
  6. 100
  7. energy used each second
  8. 41
  9. 120
  10. 1 kilowatt-hour (kWh)
  11. 100
  12. 10
  13. 1.2
  14. a motor
  15. 3
  16. 3
  17. gets smaller
  18. False
  19. a buzzer
  20. 12
  21. run fans in empty rooms
  22. 85
  23. 520
  24. 460
  25. 3
  26. 0.1
  27. 20
  28. watt (W)
  29. energy used each second
  30. cathode (−)
  31. ammeter
  32. 570
  33. 15
  34. green-brown-brown
  35. P = V × I
  36. the push of a cell
  37. False
  38. leave the TV on standby
  39. 459
  40. 50

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