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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 806 · 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.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  2. 2.🌈 Which band is read first on a resistor? (a) the widest gap (b) the gold band (c) any band (d) the one nearest an end
  3. 3.📏 How many watts (W) is 3.7 kW?
  4. 4.🔺 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
  5. 5.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) their sum (c) always zero (d) more than either one
  6. 6.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) smaller (c) stay the same (d) bigger
  7. 7.📏 Which unit measures current? (a) watt (W) (b) volt (V) (c) ohm (Ω) (d) ampere (A)
  8. 8.🌈 In the resistor colour code, which number does black stand for?
  9. 9.🔺 A current of 40 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  10. 10.What does a capacitor do? (a) senses how bright it is (b) blows if current is high (c) makes a beeping sound (d) smooths a wobbly supply
  11. 11.🔺 A 20 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  12. 12.🔺 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
  13. 13.⚡ A 6 W device works on 6 V. What current does it take (in amperes)? =
  14. 14.True or false: a transistor blows if current is high. (a) True (b) False
  15. 15.📏 How many amperes (A) is 1960 mA? =
  16. 16.🔺 A 10 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
  17. 17.🔺 A current of 50 mA flows when 16.5 V is joined across a resistor. What is its resistance (in ohms)?
  18. 18.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
  19. 19.💡 An LED is joined to a 6 V battery through a 220 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) may burn out (b) lights up (c) does not light
  20. 20.📏 How many kilo-ohms (kΩ) is 2500 Ω? =
  21. 21.📏 In the water-pipe picture of a circuit, resistance is like … (a) a bigger tank (b) the water pressure (c) a narrow pipe (d) the flow of water
  22. 22.🔍 Which is the odd one out? (a) use old filament bulbs (b) use daylight to read (c) leave the TV on standby (d) leave fridge door open
  23. 23.🧩 A capacitor in a circuit can … (a) make light (b) spin a wheel (c) measure heat (d) store charge briefly
  24. 24.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = V × I (d) P = I ÷ V
  25. 25.🧮 Three equal 75 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  26. 26.🔺 A current of 50 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  27. 27.🔺 A 3 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  28. 28.🧮 Five equal 25 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  29. 29.📏 Which unit measures how much a part resists? (a) watt (W) (b) volt (V) (c) ampere (A) (d) ohm (Ω)
  30. 30.🔺 A current of 20 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.🧮 A 5 V battery is joined to 12 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
  32. 32.🔺 An 11 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
  33. 33.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 50 % (c) 25 % (d) 5 %
  34. 34.True or false: a fuse senses how bright it is. (a) True (b) False
  35. 35.📏 How many watts (W) is 0.4 kW?
  36. 36.🔺 A current of 10 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  37. 37.🔺 A current of 20 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  38. 38.🔺 A 3 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  39. 39.🔺 A current of 3 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  40. 40.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False

Answer key

  1. cathode (−)
  2. the one nearest an end
  3. 3700
  4. R = V ÷ I
  5. less than either one
  6. bigger
  7. ampere (A)
  8. 0
  9. 20
  10. smooths a wobbly supply
  11. 40
  12. I = V ÷ R
  13. 1
  14. False
  15. 1.96
  16. 40
  17. 330
  18. True
  19. does not light
  20. 2.5
  21. a narrow pipe
  22. use daylight to read
  23. store charge briefly
  24. P = V × I
  25. 25
  26. 6
  27. 0.25
  28. 5
  29. ohm (Ω)
  30. 5
  31. 0.25
  32. 50
  33. 5 %
  34. False
  35. 400
  36. 4.7
  37. 100
  38. 0.2
  39. 60
  40. False

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