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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 663 · 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.📏 Which unit measures power? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
  2. 2.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  3. 3.🔺 A 4 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  4. 4.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 5 % (d) 0 %
  5. 5.What does an LED do? (a) is a resistance knob (b) makes a beeping sound (c) stores a little charge (d) glows using little power
  6. 6.🧮 A 0.7 V battery is joined to 2 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
  7. 7.🔺 A 12 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  8. 8.True or false: a resistor limits the current. (a) False (b) True
  9. 9.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  10. 10.🧮 Resistors of 10 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
  11. 11.💡 A red LED uses 2 V and should get 10 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
  12. 12.⚡ A 4.8 W device works on 24 V. What current does it take (in amperes)? =
  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 9 hours. How many watt-hours (Wh) are saved?
  14. 14.True or false: energy used each second is measured in amperes (A). (a) True (b) False
  15. 15.🧮 Four equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  16. 16.Which of these is measured in amperes (A)? (a) energy used each second (b) resistance (c) voltage (d) the flow of charge
  17. 17.True or false: the ammeter measures current. (a) False (b) True
  18. 18.True or false: the flow of charge is measured in amperes (A). (a) False (b) True
  19. 19.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  20. 20.🧮 A 47 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  21. 21.🔺 A current of 40 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  22. 22.📏 How many kilowatts (kW) is 300 W? =
  23. 23.🔺 A current of 40 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  24. 24.🌈 Which band is read first on a resistor? (a) any band (b) the gold band (c) the widest gap (d) the one nearest an end
  25. 25.🔺 A current of 40 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  26. 26.True or false: an LED limits the current. (a) False (b) True
  27. 27.🌈 A resistor has the colour bands green, blue, orange. What is its value in kilo-ohms (kΩ)? =
  28. 28.🔺 A current of 3 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  29. 29.🔺 A current of 10 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.🔺 A current of 0.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.True or false: how much a part resists is measured in ohms (Ω). (a) True (b) False
  32. 32.🧩 Which component glows using little power? (a) thermistor (b) LDR (c) LED (d) potentiometer
  33. 33.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to an 8 V supply. What current flows (in mA)?
  34. 34.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  35. 35.Which of these saves electricity? (a) iron one shirt at a time (b) switch off empty rooms (c) use old filament bulbs (d) leave the TV on standby
  36. 36.⚡ A 48 W device works on 24 V. What current does it take (in amperes)? =
  37. 37.🧮 A 14 V battery is joined to 12 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
  38. 38.📏 How many amperes (A) is 1590 mA? =
  39. 39.🔺 A current of 1 A flows when 15 V is joined across a resistor. What is its resistance (in ohms)?
  40. 40.🌈 A resistor has the colour bands brown, red, orange. What is its value (in ohms)?

Answer key

  1. watt (W)
  2. 1.2
  3. 40
  4. 5 %
  5. glows using little power
  6. 0.1
  7. 1.5
  8. True
  9. anode (+)
  10. 480
  11. 1000
  12. 0.2
  13. 567
  14. False
  15. 50
  16. the flow of charge
  17. True
  18. True
  19. 100
  20. 52
  21. 20
  22. 0.3
  23. 13.2
  24. the one nearest an end
  25. 16
  26. False
  27. 56
  28. 24
  29. 4.7
  30. 2.5
  31. True
  32. LED
  33. 20
  34. 500
  35. switch off empty rooms
  36. 2
  37. 1
  38. 1.59
  39. 15
  40. 12000

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