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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 109 · 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 resistor has the colour bands brown, white, red. What is its value (in ohms)?
  2. 2.🧮 Three equal 60 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  3. 3.⚡ A device works on 24 V and takes 0.2 A. What is its power (in watts)? =
  4. 4.🔺 A 3.75 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  5. 5.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) stays the same (c) gets bigger (d) gets smaller
  6. 6.🔍 Which is the odd one out? (a) use old filament bulbs (b) leave the TV on standby (c) use LED lamps (d) run fans in empty rooms
  7. 7.Which of these saves electricity? (a) leave the TV on standby (b) run fans in empty rooms (c) use old filament bulbs (d) switch off empty rooms
  8. 8.⚡ A 6 W device works on 3 V. What current does it take (in amperes)? =
  9. 9.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  10. 10.🧾 A 1500 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
  11. 11.📏 Which unit measures resistance? (a) volt (V) (b) watt (W) (c) ampere (A) (d) ohm (Ω)
  12. 12.🧩 Which component turns a fan or wheels? (a) transistor (b) capacitor (c) fuse (d) motor
  13. 13.Which of these wastes electricity? (a) set the AC to 24 °C (b) close the fridge quickly (c) run fans in empty rooms (d) use LED lamps
  14. 14.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  15. 15.🧩 Which component makes a beeping sound? (a) LDR (b) buzzer (c) fuse (d) capacitor
  16. 16.True or false: a capacitor smooths a wobbly supply. (a) False (b) True
  17. 17.⚡ A device works on 1.5 V and takes 1 A. What is its power (in watts)? =
  18. 18.🌈 A resistor has the colour bands grey, yellow, red. What is its value (in ohms)?
  19. 19.🔺 A 16 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  20. 20.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
  21. 21.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V × I (c) P = V + I (d) P = V ÷ I
  22. 22.🔍 Which is the odd one out? (a) leave the TV on standby (b) leave fridge door open (c) use old filament bulbs (d) close the fridge quickly
  23. 23.True or false: the voltmeter measures current. (a) True (b) False
  24. 24.True or false: voltage is measured in amperes (A). (a) True (b) False
  25. 25.📏 How many watts (W) is 2.3 kW?
  26. 26.🧩 Which component has coloured bands? (a) buzzer (b) thermistor (c) resistor (d) transistor
  27. 27.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) zero (c) bigger (d) stay the same
  28. 28.🌈 In the resistor colour code, which number does yellow stand for?
  29. 29.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
  30. 30.🌈 A resistor has the colour bands violet, blue, black. What is its value (in ohms)?
  31. 31.Which of these is measured in watts (W)? (a) power (b) how much a part resists (c) resistance (d) voltage
  32. 32.🧾 A 2000 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
  33. 33.🌈 A resistor has the colour bands white, white, brown. What is its value (in ohms)?
  34. 34.💡 Does it save or waste electricity to run fans in empty rooms? (a) saves electricity (b) wastes electricity
  35. 35.⚡ A 1.2 W device works on 12 V. What current does it take (in amperes)? =
  36. 36.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  37. 37.🧾 A family uses 60 units of electricity in a month and each unit costs ₹8. What is the bill (in ₹)?
  38. 38.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 5 % (c) 0 % (d) 25 %
  39. 39.⚡ Power tells us … (a) the colour of light (b) the size of a cell (c) the length of a wire (d) energy used each second
  40. 40.🔺 A current of 2.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =

Answer key

  1. 1900
  2. 20
  3. 4.8
  4. 25
  5. gets smaller
  6. use LED lamps
  7. switch off empty rooms
  8. 2
  9. 165
  10. 6
  11. ohm (Ω)
  12. motor
  13. run fans in empty rooms
  14. cathode (−)
  15. buzzer
  16. True
  17. 1.5
  18. 8400
  19. 40
  20. False
  21. P = V × I
  22. close the fridge quickly
  23. False
  24. False
  25. 2300
  26. resistor
  27. bigger
  28. 4
  29. voltmeter
  30. 76
  31. power
  32. 8
  33. 990
  34. wastes electricity
  35. 0.1
  36. 1
  37. 480
  38. 5 %
  39. energy used each second
  40. 30

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