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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 664 · 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 40 mA flows when 8 V is joined across a resistor. What is its resistance (in ohms)?
  2. 2.True or false: a buzzer makes a beeping sound. (a) False (b) True
  3. 3.What does a buzzer do? (a) glows using little power (b) is a resistance knob (c) senses how hot it is (d) beeps for an alarm
  4. 4.🔺 A 1.6 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  5. 5.⚡ A device works on 3 V and takes 1 A. What is its power (in watts)? =
  6. 6.🔺 A current of 0.25 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  7. 7.🔺 A current of 50 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  8. 8.📏 Which unit measures current? (a) ohm (Ω) (b) ampere (A) (c) watt (W) (d) volt (V)
  9. 9.What does a fuse do? (a) smooths a wobbly supply (b) blows if current is high (c) makes a beeping sound (d) is a resistance knob
  10. 10.Which of these wastes electricity? (a) set the AC to 24 °C (b) iron one shirt at a time (c) close the fridge quickly (d) switch off empty rooms
  11. 11.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 3 hours. How many watt-hours (Wh) are saved?
  12. 12.🔺 A current of 3 A flows when 15 V is joined across a resistor. What is its resistance (in ohms)?
  13. 13.📏 Which unit measures how much a part resists? (a) watt (W) (b) ohm (Ω) (c) ampere (A) (d) volt (V)
  14. 14.🔺 A current of 50 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.🔍 Which is the odd one out? (a) run fans in empty rooms (b) unplug idle chargers (c) set the AC to 24 °C (d) use LED lamps
  16. 16.🌈 In the resistor colour code, which number does brown stand for?
  17. 17.💡 A red LED uses 2 V and should get 20 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
  18. 18.🧾 A family uses 140 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
  19. 19.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  20. 20.🌈 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
  21. 21.🔺 A current of 0.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  22. 22.⚡ A device works on 1.5 V and takes 1.5 A. What is its power (in watts)? =
  23. 23.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
  24. 24.🔍 Which is the odd one out? (a) leave fridge door open (b) close the fridge quickly (c) leave the TV on standby (d) iron one shirt at a time
  25. 25.🔺 A current of 0.1 A flows when 0.2 V is joined across a resistor. What is its resistance (in ohms)?
  26. 26.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 41000 Ω resistor? (a) yellow-brown-red (b) brown-yellow-orange (c) yellow-brown-orange (d) yellow-brown-yellow
  27. 27.🌈 A resistor has the colour bands orange, black, black. What is its value (in ohms)?
  28. 28.⚡ A device works on 12 V and takes 3 A. What is its power (in watts)? =
  29. 29.Which of these is measured in volts (V)? (a) power (b) energy used each second (c) the push of a cell (d) the flow of charge
  30. 30.🧮 A 3.5 V battery is joined to 5 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
  31. 31.What does a thermistor do? (a) senses how hot it is (b) has coloured bands (c) lets current go one way (d) blows if current is high
  32. 32.🧩 A capacitor in a circuit can … (a) store charge briefly (b) make light (c) measure heat (d) spin a wheel
  33. 33.⚡ A device works on 12 V and takes 2 A. What is its power (in watts)? =
  34. 34.🔺 A current of 2.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.🌈 A resistor has the colour bands yellow, violet, brown. What is its value (in ohms)?
  36. 36.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 8 hours. How many watt-hours (Wh) are saved?
  37. 37.🔺 A current of 25 mA flows when 3.75 V is joined across a resistor. What is its resistance (in ohms)?
  38. 38.🧮 Five equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  39. 39.🔺 A current of 25 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  40. 40.True or false: an LDR senses how bright it is. (a) True (b) False

Answer key

  1. 200
  2. True
  3. beeps for an alarm
  4. 0.2
  5. 3
  6. 1.25
  7. 6
  8. ampere (A)
  9. blows if current is high
  10. iron one shirt at a time
  11. 102
  12. 5
  13. ohm (Ω)
  14. 15
  15. run fans in empty rooms
  16. 1
  17. 500
  18. 560
  19. anode (+)
  20. the one nearest an end
  21. 2
  22. 2.25
  23. voltmeter
  24. close the fridge quickly
  25. 2
  26. yellow-brown-orange
  27. 30
  28. 36
  29. the push of a cell
  30. 0.5
  31. senses how hot it is
  32. store charge briefly
  33. 24
  34. 50
  35. 470
  36. 504
  37. 150
  38. 20
  39. 2.5
  40. True

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