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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 733 · 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 25 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  2. 2.⚡ Which formula gives electric power? (a) P = V × I (b) P = I ÷ V (c) P = V + I (d) P = V ÷ I
  3. 3.🔍 Which is the odd one out? (a) use old filament bulbs (b) iron one shirt at a time (c) run fans in empty rooms (d) set the AC to 24 °C
  4. 4.🔺 A current of 10 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  5. 5.💡 Why does an LED need a resistor in series? (a) to store charge (b) to make it brighter (c) to limit the current (d) to change its colour
  6. 6.🌈 A resistor has the colour bands violet, violet, brown. What is its value (in ohms)?
  7. 7.🔺 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
  8. 8.🧮 Resistors of 330 Ω, 330 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
  9. 9.What does a thermistor do? (a) beeps for an alarm (b) limits the current (c) boosts a small signal (d) senses how hot it is
  10. 10.⚡ A device works on 5 V and takes 0.1 A. What is its power (in watts)? =
  11. 11.Which of these is measured in watts (W)? (a) current (b) how much a part resists (c) the push of a cell (d) energy used each second
  12. 12.What does a resistor do? (a) blows if current is high (b) has coloured bands (c) boosts a small signal (d) senses how bright it is
  13. 13.True or false: the voltmeter measures voltage. (a) False (b) True
  14. 14.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 800 Ω resistor? (a) white-grey-brown (b) grey-black-brown (c) grey-black-red (d) grey-black-black
  15. 15.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 2500 Ω resistor? (a) green-red-red (b) red-green-brown (c) red-green-orange (d) red-green-red
  16. 16.🔺 A 5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
  17. 17.True or false: a capacitor smooths a wobbly supply. (a) True (b) False
  18. 18.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 330 Ω resistor? (a) orange-orange-brown (b) orange-orange-red (c) orange-orange-black (d) orange-yellow-brown
  19. 19.🧾 A 200 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
  20. 20.Which of these saves electricity? (a) use old filament bulbs (b) run fans in empty rooms (c) leave fridge door open (d) switch off empty rooms
  21. 21.🔺 A current of 25 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  22. 22.🧮 A 22 Ω resistor is joined in series with two equal 50 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  23. 23.Which of these wastes electricity? (a) use daylight to read (b) close the fridge quickly (c) iron one shirt at a time (d) use LED lamps
  24. 24.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  25. 25.🧮 Three equal 15 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  26. 26.🔍 Which is the odd one out? (a) close the fridge quickly (b) set the AC to 24 °C (c) iron one shirt at a time (d) use daylight to read
  27. 27.⚡ A device works on 9 V and takes 2 A. What is its power (in watts)? =
  28. 28.⚡ An 18 W device works on 12 V. What current does it take (in amperes)? =
  29. 29.🧩 Which component boosts a small signal? (a) motor (b) buzzer (c) transistor (d) resistor
  30. 30.📏 Which unit measures energy used each second? (a) ohm (Ω) (b) watt (W) (c) ampere (A) (d) volt (V)
  31. 31.🔺 A current of 10 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  32. 32.⚡ A device works on 12 V and takes 0.1 A. What is its power (in watts)? =
  33. 33.True or false: the flow of charge is measured in amperes (A). (a) False (b) True
  34. 34.⚡ A device works on 3 V and takes 0.25 A. What is its power (in watts)? =
  35. 35.True or false: the voltmeter is joined across a part. (a) False (b) True
  36. 36.💡 A red LED uses 2 V and should get 20 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
  37. 37.🧾 Which lamp gives the same light for the least power? (a) a candle (b) a filament bulb (c) an LED lamp (d) an oil lamp
  38. 38.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I × R (c) V = I + R (d) V = I ÷ R
  39. 39.🔺 A 7.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  40. 40.🧾 A family uses 200 units of electricity in a month and each unit costs ₹9. What is the bill (in ₹)?

Answer key

  1. 7.5
  2. P = V × I
  3. set the AC to 24 °C
  4. 2.5
  5. to limit the current
  6. 770
  7. I = V ÷ R
  8. 707
  9. senses how hot it is
  10. 0.5
  11. energy used each second
  12. has coloured bands
  13. True
  14. grey-black-brown
  15. red-green-red
  16. 20
  17. True
  18. orange-orange-brown
  19. 1
  20. switch off empty rooms
  21. 2.5
  22. 47
  23. iron one shirt at a time
  24. anode (+)
  25. 5
  26. iron one shirt at a time
  27. 18
  28. 1.5
  29. transistor
  30. watt (W)
  31. 1.5
  32. 1.2
  33. True
  34. 0.75
  35. True
  36. 200
  37. an LED lamp
  38. V = I × R
  39. 50
  40. 1800

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