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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 323 · 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 1.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  2. 2.🔺 A current of 20 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  3. 3.⚡ A 36 W device works on 12 V. What current does it take (in amperes)? =
  4. 4.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V + I (c) P = V × I (d) P = V ÷ I
  5. 5.What does a fuse do? (a) makes a beeping sound (b) blows if current is high (c) boosts a small signal (d) has coloured bands
  6. 6.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 1 hour. How many watt-hours (Wh) are saved?
  7. 7.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
  8. 8.💡 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)?
  9. 9.📏 How many milliamperes (mA) is 0.31 A?
  10. 10.🔺 An 8 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  11. 11.🔺 An 11.75 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  12. 12.Which of these is measured in amperes (A)? (a) voltage (b) the flow of charge (c) resistance (d) energy used each second
  13. 13.💡 An LED is joined to a 3 V battery through a 220 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) lights up (b) may burn out (c) does not light
  14. 14.📏 How many kilo-ohms (kΩ) is 6700 Ω? =
  15. 15.🔺 A current of 50 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  16. 16.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 3 V supply. What current flows (in mA)?
  17. 17.🧮 A 1.5 V battery is joined to 12 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
  18. 18.🌈 A resistor has the colour bands violet, white, red. What is its value in kilo-ohms (kΩ)? =
  19. 19.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 810 Ω resistor? (a) grey-brown-brown (b) grey-brown-black (c) brown-grey-brown (d) grey-brown-red
  20. 20.🔺 A current of 40 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  21. 21.⚡ 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
  22. 22.🔺 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
  23. 23.💡 What does LED stand for? (a) large electric dial (b) light energy dial (c) light-emitting diode (d) low energy device
  24. 24.True or false: a diode limits the current. (a) True (b) False
  25. 25.🧮 Five equal 250 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  26. 26.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
  27. 27.🧮 Four equal 400 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  28. 28.🧮 A 1.1 V battery is joined to 5 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
  29. 29.🔺 A current of 40 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.🔺 A current of 0.1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.🧩 Which component stores a little charge? (a) potentiometer (b) LED (c) capacitor (d) motor
  32. 32.🌈 A resistor has the colour bands brown, green, red. What is its value (in ohms)?
  33. 33.🔺 A current of 0.1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  34. 34.🔺 A 10 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  35. 35.🔺 A current of 25 mA flows when 11.75 V is joined across a resistor. What is its resistance (in ohms)?
  36. 36.💡 An LED is joined to a 3 V battery through a 220 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) lights up (b) does not light (c) may burn out
  37. 37.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  38. 38.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  39. 39.⚡ A 13.5 W device works on 9 V. What current does it take (in amperes)? =
  40. 40.🧩 A capacitor in a circuit can … (a) measure heat (b) store charge briefly (c) spin a wheel (d) make light

Answer key

  1. 4.5
  2. 6.6
  3. 3
  4. P = V × I
  5. blows if current is high
  6. 63
  7. True
  8. 15
  9. 310
  10. 20
  11. 25
  12. the flow of charge
  13. does not light
  14. 6.7
  15. 16.5
  16. 5
  17. 0.1
  18. 7.9
  19. grey-brown-brown
  20. 8.8
  21. energy used each second
  22. gets smaller
  23. light-emitting diode
  24. False
  25. 50
  26. False
  27. 100
  28. 0.1
  29. 8
  30. 1.2
  31. capacitor
  32. 1500
  33. 0.3
  34. 25
  35. 470
  36. lights up
  37. cathode (−)
  38. 5
  39. 1.5
  40. store charge briefly

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