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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 441 · 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.🔺 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
  2. 2.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a diode (c) a resistor (d) a buzzer
  3. 3.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 0 % (c) 5 % (d) 50 %
  4. 4.⚡ A device works on 6 V and takes 3 A. What is its power (in watts)? =
  5. 5.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 4 hours. How many watt-hours (Wh) are saved?
  6. 6.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 3500 Ω resistor? (a) orange-green-orange (b) green-orange-red (c) orange-green-red (d) orange-green-brown
  7. 7.True or false: the ammeter measures current. (a) True (b) False
  8. 8.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3 V supply. What current flows (in mA)?
  9. 9.🧩 A capacitor in a circuit can … (a) measure heat (b) spin a wheel (c) store charge briefly (d) make light
  10. 10.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 4 V supply. What current flows (in mA)?
  11. 11.🔺 A current of 10 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  12. 12.True or false: an LDR makes things spin. (a) True (b) False
  13. 13.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  14. 14.Which of these saves electricity? (a) use old filament bulbs (b) unplug idle chargers (c) leave the TV on standby (d) iron one shirt at a time
  15. 15.🔺 A 6 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  16. 16.🧮 Two resistors in parallel give a total that is … (a) their sum (b) less than either one (c) more than either one (d) always zero
  17. 17.Which of these is measured in volts (V)? (a) energy used each second (b) power (c) voltage (d) resistance
  18. 18.🔺 A current of 2.5 A flows when 37.5 V is joined across a resistor. What is its resistance (in ohms)?
  19. 19.💡 Does it save or waste electricity to iron one shirt at a time? (a) wastes electricity (b) saves electricity
  20. 20.⚡ Which formula gives electric power? (a) P = V × I (b) P = V ÷ I (c) P = I ÷ V (d) P = V + I
  21. 21.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  22. 22.🧩 Which part changes electrical energy into movement? (a) a resistor (b) a fuse (c) a motor (d) an LED
  23. 23.🔺 A current of 10 mA flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
  24. 24.True or false: energy used each second is measured in watts (W). (a) True (b) False
  25. 25.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) becomes zero (c) gets bigger (d) gets smaller
  26. 26.🧮 Three equal 150 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  27. 27.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
  28. 28.🧮 A 1.4 V battery is joined to 8 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
  29. 29.🧾 A 2000 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
  30. 30.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 5 V supply. What current flows (in mA)?
  31. 31.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 5 hours. How many watt-hours (Wh) are saved?
  32. 32.💡 Does it save or waste electricity to leave the TV on standby? (a) saves electricity (b) wastes electricity
  33. 33.🌈 A resistor has the colour bands yellow, yellow, orange. What is its value (in ohms)?
  34. 34.True or false: current is measured in amperes (A). (a) False (b) True
  35. 35.⚡ A 3 W device works on 12 V. What current does it take (in amperes)? =
  36. 36.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 7200 Ω resistor? (a) violet-red-brown (b) red-violet-red (c) violet-red-red (d) violet-red-orange
  37. 37.🧮 Two equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  38. 38.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 watt (c) 1 volt (d) 1 kilowatt-hour (kWh)
  39. 39.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
  40. 40.True or false: the voltmeter is joined across a part. (a) False (b) True

Answer key

  1. R = V ÷ I
  2. a buzzer
  3. 5 %
  4. 18
  5. 204
  6. orange-green-red
  7. True
  8. 10
  9. store charge briefly
  10. 20
  11. 2
  12. False
  13. 235
  14. unplug idle chargers
  15. 2
  16. less than either one
  17. voltage
  18. 15
  19. wastes electricity
  20. P = V × I
  21. 1.2
  22. a motor
  23. 100
  24. True
  25. gets smaller
  26. 50
  27. voltmeter
  28. 0.1
  29. 8
  30. 15
  31. 170
  32. wastes electricity
  33. 44000
  34. True
  35. 0.25
  36. violet-red-red
  37. 50
  38. 1 kilowatt-hour (kWh)
  39. False
  40. True

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