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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 224 · 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 20 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  2. 2.🌈 A resistor has the colour bands blue, brown, orange. What is its value in kilo-ohms (kΩ)? =
  3. 3.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
  4. 4.🧩 Which component is a resistance knob? (a) fuse (b) transistor (c) potentiometer (d) resistor
  5. 5.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = R ÷ I (c) V = I × R (d) V = I ÷ R
  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.🔺 A current of 1.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  8. 8.🧩 Which component glows using little power? (a) buzzer (b) resistor (c) LED (d) fuse
  9. 9.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 6 hours. How many watt-hours (Wh) are saved?
  10. 10.True or false: energy used each second is measured in volts (V). (a) False (b) True
  11. 11.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to store charge (c) to limit the current (d) to make it brighter
  12. 12.🌈 A resistor has the colour bands blue, violet, red. What is its value (in ohms)?
  13. 13.📏 Which unit measures resistance? (a) ampere (A) (b) watt (W) (c) ohm (Ω) (d) volt (V)
  14. 14.🔺 A 2.4 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  15. 15.🌈 Which band is read first on a resistor? (a) the widest gap (b) any band (c) the one nearest an end (d) the gold band
  16. 16.🧮 Resistors of 330 Ω and 220 Ω are joined in series. What is the total resistance (in ohms)?
  17. 17.💡 An LED is joined to a 3 V battery through a 1000 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
  18. 18.🧮 Resistors of 50 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
  19. 19.True or false: a motor makes things spin. (a) False (b) True
  20. 20.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) zero (c) smaller (d) stay the same
  21. 21.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 15 Ω resistor? (a) brown-green-brown (b) green-brown-black (c) brown-green-black (d) red-green-black
  22. 22.True or false: to iron one shirt at a time saves electricity. (a) True (b) False
  23. 23.True or false: voltage is measured in watts (W). (a) False (b) True
  24. 24.⚡ A device works on 3 V and takes 1.5 A. What is its power (in watts)? =
  25. 25.Which of these saves electricity? (a) unplug idle chargers (b) run fans in empty rooms (c) iron one shirt at a time (d) use old filament bulbs
  26. 26.What does a potentiometer do? (a) makes things spin (b) is a resistance knob (c) boosts a small signal (d) smooths a wobbly supply
  27. 27.🌈 A resistor has the colour bands white, blue, orange. What is its value in kilo-ohms (kΩ)? =
  28. 28.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  29. 29.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
  30. 30.🔺 A current of 20 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 43000 Ω resistor? (a) orange-yellow-orange (b) yellow-orange-red (c) yellow-orange-orange (d) yellow-orange-yellow
  32. 32.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 3.5 V supply. What current flows (in mA)?
  33. 33.🧩 A capacitor in a circuit can … (a) spin a wheel (b) measure heat (c) store charge briefly (d) make light
  34. 34.🔺 In the V-I-R triangle, how do we find R? (a) R = V + I (b) R = V ÷ I (c) R = I ÷ V (d) R = V × I
  35. 35.Which of these wastes electricity? (a) iron one shirt at a time (b) use LED lamps (c) switch off empty rooms (d) close the fridge quickly
  36. 36.🔺 A 25 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  37. 37.🔺 A current of 2.5 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  38. 38.🧮 Resistors of 47 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
  39. 39.Which of these is measured in watts (W)? (a) energy used each second (b) how much a part resists (c) the push of a cell (d) voltage
  40. 40.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 30000 Ω resistor? (a) orange-black-orange (b) yellow-orange-orange (c) orange-black-red (d) orange-black-yellow

Answer key

  1. 2
  2. 61
  3. 460
  4. potentiometer
  5. V = I × R
  6. P = V × I
  7. 3
  8. LED
  9. 306
  10. False
  11. to limit the current
  12. 6700
  13. ohm (Ω)
  14. 20
  15. the one nearest an end
  16. 550
  17. lights up
  18. 72
  19. True
  20. bigger
  21. brown-green-black
  22. False
  23. False
  24. 4.5
  25. unplug idle chargers
  26. is a resistance knob
  27. 96
  28. anode (+)
  29. voltmeter
  30. 9.4
  31. yellow-orange-orange
  32. 10
  33. store charge briefly
  34. R = V ÷ I
  35. iron one shirt at a time
  36. 50
  37. 37.5
  38. 94
  39. energy used each second
  40. orange-black-orange

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