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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 987 · 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 1 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  2. 2.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  3. 3.🌈 A resistor has the colour bands grey, white, orange. What is its value (in ohms)?
  4. 4.💡 Does it save or waste electricity to run fans in empty rooms? (a) wastes electricity (b) saves electricity
  5. 5.🔺 A current of 10 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V ÷ I (c) R = V × I (d) R = V + I
  7. 7.🧮 Resistors of 22 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
  8. 8.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
  9. 9.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
  10. 10.💡 Does it save or waste electricity to use LED lamps? (a) saves electricity (b) wastes electricity
  11. 11.🔺 A 5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
  12. 12.True or false: the voltmeter measures voltage. (a) True (b) False
  13. 13.🌈 In the resistor colour code, which number does brown stand for?
  14. 14.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
  15. 15.True or false: the flow of charge is measured in volts (V). (a) False (b) True
  16. 16.Which of these saves electricity? (a) use old filament bulbs (b) use LED lamps (c) iron one shirt at a time (d) leave the TV on standby
  17. 17.True or false: to use daylight to read wastes electricity. (a) True (b) False
  18. 18.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 0 % (c) 50 % (d) 5 %
  19. 19.🌈 A resistor has the colour bands white, grey, red. What is its value (in ohms)?
  20. 20.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 2 hours. How many watt-hours (Wh) are saved?
  21. 21.🌈 In the resistor colour code, which number does violet stand for?
  22. 22.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to make it brighter (c) to limit the current (d) to store charge
  23. 23.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 6 V supply. What current flows (in mA)?
  24. 24.🧾 A 50 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
  25. 25.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = I × R (c) V = I ÷ R (d) V = R ÷ I
  26. 26.True or false: a fuse smooths a wobbly supply. (a) True (b) False
  27. 27.🧾 A family uses 110 units of electricity in a month and each unit costs ₹8. What is the bill (in ₹)?
  28. 28.🔺 A 15 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  29. 29.🌈 A resistor has the colour bands grey, orange, red. What is its value in kilo-ohms (kΩ)? =
  30. 30.What does a buzzer do? (a) stores a little charge (b) blows if current is high (c) beeps for an alarm (d) senses how hot it is
  31. 31.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 28000 Ω resistor? (a) red-grey-orange (b) red-grey-yellow (c) red-grey-red (d) grey-red-orange
  32. 32.Which of these saves electricity? (a) leave the TV on standby (b) leave fridge door open (c) switch off empty rooms (d) iron one shirt at a time
  33. 33.🔺 A current of 20 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  34. 34.🔺 A 2 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  35. 35.🔺 A current of 20 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.💡 Does it save or waste electricity to switch off empty rooms? (a) saves electricity (b) wastes electricity
  37. 37.🔺 A 10 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  38. 38.🔍 Which is the odd one out? (a) run fans in empty rooms (b) unplug idle chargers (c) leave the TV on standby (d) leave fridge door open
  39. 39.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 680 Ω resistor? (a) blue-grey-red (b) blue-grey-brown (c) blue-grey-black (d) grey-blue-brown
  40. 40.🔍 Which is the odd one out? (a) switch off empty rooms (b) use daylight to read (c) set the AC to 24 °C (d) leave fridge door open

Answer key

  1. 10
  2. anode (+)
  3. 89000
  4. wastes electricity
  5. 5
  6. R = V ÷ I
  7. 352
  8. voltmeter
  9. 1150
  10. saves electricity
  11. 20
  12. True
  13. 1
  14. 1840
  15. False
  16. use LED lamps
  17. False
  18. 5 %
  19. 9800
  20. 126
  21. 7
  22. to limit the current
  23. 20
  24. 0.4
  25. V = I × R
  26. False
  27. 880
  28. 3
  29. 8.3
  30. beeps for an alarm
  31. red-grey-orange
  32. switch off empty rooms
  33. 4.4
  34. 0.5
  35. 2
  36. saves electricity
  37. 2
  38. unplug idle chargers
  39. blue-grey-brown
  40. leave fridge door open

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