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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 763 · 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 current of 0.2 A flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
  2. 2.⚡ 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
  3. 3.🧮 A 50 Ω resistor is joined in series with two equal 40 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  4. 4.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  5. 5.💡 What does LED stand for? (a) light energy dial (b) light-emitting diode (c) large electric dial (d) low energy device
  6. 6.True or false: to unplug idle chargers wastes electricity. (a) False (b) True
  7. 7.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 70 Ω resistor? (a) violet-black-black (b) grey-black-black (c) violet-black-brown (d) grey-violet-black
  8. 8.🌈 A resistor has the colour bands white, violet, red. What is its value (in ohms)?
  9. 9.True or false: how much a part resists is measured in volts (V). (a) False (b) True
  10. 10.📏 Which unit measures energy used each second? (a) ampere (A) (b) volt (V) (c) ohm (Ω) (d) watt (W)
  11. 11.🔍 Which is the odd one out? (a) unplug idle chargers (b) switch off empty rooms (c) leave fridge door open (d) set the AC to 24 °C
  12. 12.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  13. 13.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 6 hours. How many watt-hours (Wh) are saved?
  14. 14.🔺 A current of 1 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  15. 15.Which of these saves electricity? (a) iron one shirt at a time (b) switch off empty rooms (c) leave fridge door open (d) run fans in empty rooms
  16. 16.🌈 A resistor has the colour bands grey, grey, red. What is its value (in ohms)?
  17. 17.🔺 In the V-I-R triangle, how do we find R? (a) R = V + I (b) R = V × I (c) R = V ÷ I (d) R = I ÷ V
  18. 18.🌈 A resistor has the colour bands white, blue, yellow. What is its value in kilo-ohms (kΩ)? =
  19. 19.🧾 Which lamp gives the same light for the least power? (a) a candle (b) an oil lamp (c) a filament bulb (d) an LED lamp
  20. 20.🌈 A resistor has the colour bands red, red, brown. What is its value (in ohms)?
  21. 21.🌈 In the resistor colour code, which number does orange stand for?
  22. 22.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 kilowatt-hour (kWh) (c) 1 ampere (d) 1 watt
  23. 23.Which of these wastes electricity? (a) set the AC to 24 °C (b) use LED lamps (c) unplug idle chargers (d) run fans in empty rooms
  24. 24.🔺 A current of 10 mA flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  25. 25.Which of these saves electricity? (a) use old filament bulbs (b) leave fridge door open (c) run fans in empty rooms (d) use LED lamps
  26. 26.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V ÷ I (c) P = V + I (d) P = V × I
  27. 27.🧮 Resistors of 33 Ω, 47 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
  28. 28.🔺 A current of 2.5 A flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  29. 29.🌈 A resistor has the colour bands violet, white, orange. What is its value (in ohms)?
  30. 30.🔺 A current of 0.2 A flows when 2.4 V is joined across a resistor. What is its resistance (in ohms)?
  31. 31.🌈 A resistor has the colour bands violet, violet, orange. What is its value (in ohms)?
  32. 32.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 4.25 V supply. What current flows (in mA)?
  33. 33.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  34. 34.📏 In the water-pipe picture of a circuit, voltage is like … (a) the tap handle (b) the water pressure (c) the pipe colour (d) the water tank lid
  35. 35.🧮 A 20 Ω resistor is joined in series with two equal 20 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  36. 36.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = I ÷ R (c) V = R ÷ I (d) V = I × R
  37. 37.🔺 A current of 2.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  38. 38.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 50 % (c) 0 % (d) 25 %
  39. 39.True or false: current is measured in amperes (A). (a) True (b) False
  40. 40.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3.5 V supply. What current flows (in mA)?

Answer key

  1. 5
  2. energy used each second
  3. 70
  4. cathode (−)
  5. light-emitting diode
  6. False
  7. violet-black-black
  8. 9700
  9. False
  10. watt (W)
  11. leave fridge door open
  12. cathode (−)
  13. 378
  14. 2
  15. switch off empty rooms
  16. 8800
  17. R = V ÷ I
  18. 960
  19. an LED lamp
  20. 220
  21. 3
  22. 1 kilowatt-hour (kWh)
  23. run fans in empty rooms
  24. 300
  25. use LED lamps
  26. P = V × I
  27. 230
  28. 4
  29. 79000
  30. 12
  31. 77000
  32. 15
  33. 1
  34. the water pressure
  35. 30
  36. V = I × R
  37. 20
  38. 5 %
  39. True
  40. 15

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