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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 924 · 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 colour bands (1st digit, 2nd digit, multiplier) mark a 240 Ω resistor? (a) yellow-red-brown (b) red-yellow-red (c) red-yellow-brown (d) red-yellow-black
  2. 2.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  3. 3.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to limit the current (c) to make it brighter (d) to store charge
  4. 4.🔺 A current of 1 A flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
  5. 5.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.⚡ Which formula gives electric power? (a) P = V × I (b) P = V + I (c) P = I ÷ V (d) P = V ÷ I
  7. 7.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 100 (b) 10 (c) 1000 (d) 1024
  8. 8.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = R ÷ V (c) I = V ÷ R (d) I = V + R
  9. 9.🔺 A current of 25 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  10. 10.🌈 A resistor has the colour bands blue, orange, orange. What is its value (in ohms)?
  11. 11.📏 How many milliamperes (mA) is 2.54 A?
  12. 12.🧮 A 330 Ω resistor is joined in series with two equal 100 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  13. 13.True or false: the ammeter measures current. (a) False (b) True
  14. 14.🔺 A current of 10 mA flows when 4.7 V is joined across a resistor. What is its resistance (in ohms)?
  15. 15.🔺 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
  16. 16.🔺 A 1.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  17. 17.🌈 A resistor has the colour bands green, white, red. What is its value in kilo-ohms (kΩ)? =
  18. 18.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 ampere (c) 1 volt (d) 1 kilowatt-hour (kWh)
  19. 19.🔺 A 0.75 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  20. 20.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
  21. 21.🔺 A current of 1 A flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
  22. 22.💡 An LED is joined to a 6 V battery through a 470 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) does not light (b) may burn out (c) lights up
  23. 23.📏 How many kilo-ohms (kΩ) is 3600 Ω? =
  24. 24.🧮 Three equal 60 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  25. 25.What does a capacitor do? (a) makes things spin (b) beeps for an alarm (c) stores a little charge (d) turns a fan or wheels
  26. 26.🔺 A current of 25 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  27. 27.🧮 Two resistors in parallel give a total that is … (a) their sum (b) always zero (c) more than either one (d) less than either one
  28. 28.🧮 Resistors of 330 Ω, 47 Ω, 50 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
  29. 29.💡 An LED is joined to a 9 V battery through a 330 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) lights up (b) may burn out (c) does not light
  30. 30.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = I ÷ V (c) R = V + I (d) R = V ÷ I
  31. 31.🌈 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
  32. 32.🔺 A current of 0.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  33. 33.📏 How many ohms (Ω) is 4.5 kΩ?
  34. 34.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 5100 Ω resistor? (a) green-brown-brown (b) green-brown-orange (c) brown-green-red (d) green-brown-red
  35. 35.🧩 A capacitor in a circuit can … (a) measure heat (b) spin a wheel (c) store charge briefly (d) make light
  36. 36.🔺 A current of 25 mA flows when 12.5 V is joined across a resistor. What is its resistance (in ohms)?
  37. 37.What does a motor do? (a) blows if current is high (b) boosts a small signal (c) lets current go one way (d) makes things spin
  38. 38.💡 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?
  39. 39.⚡ A 4.8 W device works on 24 V. What current does it take (in amperes)? =
  40. 40.🧩 Which part changes electrical energy into movement? (a) a resistor (b) an LED (c) a fuse (d) a motor

Answer key

  1. red-yellow-brown
  2. cathode (−)
  3. to limit the current
  4. 4
  5. 1.2
  6. P = V × I
  7. 1000
  8. I = V ÷ R
  9. 11.75
  10. 63000
  11. 2540
  12. 380
  13. True
  14. 470
  15. V = I × R
  16. 10
  17. 5.9
  18. 1 kilowatt-hour (kWh)
  19. 0.25
  20. voltmeter
  21. 20
  22. lights up
  23. 3.6
  24. 20
  25. stores a little charge
  26. 200
  27. less than either one
  28. 460
  29. does not light
  30. R = V ÷ I
  31. the one nearest an end
  32. 3
  33. 4500
  34. green-brown-red
  35. store charge briefly
  36. 500
  37. makes things spin
  38. 1000
  39. 0.2
  40. a motor

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