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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 226 · 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 0.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  2. 2.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 5 hours. How many watt-hours (Wh) are saved?
  3. 3.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 volt (c) 1 watt (d) 1 kilowatt-hour (kWh)
  4. 4.🔺 A 5 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  5. 5.🔺 A current of 10 mA flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
  6. 6.Which of these saves electricity? (a) use old filament bulbs (b) set the AC to 24 °C (c) leave fridge door open (d) leave the TV on standby
  7. 7.⚡ A 12 W device works on 24 V. What current does it take (in amperes)? =
  8. 8.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
  9. 9.⚡ A 3 W device works on 12 V. What current does it take (in amperes)? =
  10. 10.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) less than either one (c) always zero (d) their sum
  11. 11.🔺 A current of 25 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  12. 12.🔺 A current of 10 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  13. 13.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  14. 14.What does a motor do? (a) makes things spin (b) blows if current is high (c) has coloured bands (d) senses how bright it is
  15. 15.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  16. 16.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  17. 17.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) smaller (c) stay the same (d) bigger
  18. 18.⚡ A 3 W device works on 6 V. What current does it take (in amperes)? =
  19. 19.🧮 Three equal 300 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  20. 20.🌈 A resistor has the colour bands orange, black, brown. What is its value (in ohms)?
  21. 21.🔺 A current of 0.1 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  22. 22.True or false: the flow of charge is measured in amperes (A). (a) False (b) True
  23. 23.🔺 A 5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
  24. 24.🌈 A resistor has the colour bands yellow, black, red. What is its value (in ohms)?
  25. 25.💡 A red LED uses 2 V and should get 10 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  26. 26.True or false: on an LED, the shorter leg is the anode (+). (a) True (b) False
  27. 27.🌈 Which band is read first on a resistor? (a) the gold band (b) the widest gap (c) the one nearest an end (d) any band
  28. 28.🔍 Which is the odd one out? (a) use LED lamps (b) leave the TV on standby (c) run fans in empty rooms (d) use old filament bulbs
  29. 29.💡 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)?
  30. 30.💡 Does it save or waste electricity to switch off empty rooms? (a) saves electricity (b) wastes electricity
  31. 31.💡 What does LED stand for? (a) light-emitting diode (b) light energy dial (c) low energy device (d) large electric dial
  32. 32.🧮 Resistors of 100 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
  33. 33.📏 In the water-pipe picture of a circuit, resistance is like … (a) a narrow pipe (b) a bigger tank (c) the flow of water (d) the water pressure
  34. 34.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 0 % (c) 50 % (d) 5 %
  35. 35.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 4200 Ω resistor? (a) yellow-red-red (b) red-yellow-red (c) yellow-red-orange (d) yellow-red-brown
  36. 36.True or false: an LED glows using little power. (a) False (b) True
  37. 37.🔍 Which is the odd one out? (a) switch off empty rooms (b) use old filament bulbs (c) leave the TV on standby (d) iron one shirt at a time
  38. 38.🧩 Which component makes a beeping sound? (a) resistor (b) potentiometer (c) buzzer (d) LDR
  39. 39.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V ÷ R (c) I = R ÷ V (d) I = V + R
  40. 40.True or false: to switch off empty rooms wastes electricity. (a) False (b) True

Answer key

  1. 2.5
  2. 255
  3. 1 kilowatt-hour (kWh)
  4. 2.5
  5. 150
  6. set the AC to 24 °C
  7. 0.5
  8. True
  9. 0.25
  10. less than either one
  11. 3
  12. 3
  13. cathode (−)
  14. makes things spin
  15. anode (+)
  16. anode (+)
  17. bigger
  18. 0.5
  19. 100
  20. 300
  21. 0.4
  22. True
  23. 20
  24. 4000
  25. 300
  26. False
  27. the one nearest an end
  28. use LED lamps
  29. 15
  30. saves electricity
  31. light-emitting diode
  32. 570
  33. a narrow pipe
  34. 5 %
  35. yellow-red-red
  36. True
  37. switch off empty rooms
  38. buzzer
  39. I = V ÷ R
  40. False

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