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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 25 · 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 6.6 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
  2. 2.🔺 A current of 2.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  3. 3.🔺 A current of 0.2 A flows when 1.6 V is joined across a resistor. What is its resistance (in ohms)?
  4. 4.🧮 Resistors of 20 Ω, 22 Ω, 220 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
  5. 5.🧮 Three equal 15 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  6. 6.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  7. 7.⚡ A device works on 9 V and takes 0.5 A. What is its power (in watts)? =
  8. 8.🔺 A current of 20 mA flows when 2.4 V is joined across a resistor. What is its resistance (in ohms)?
  9. 9.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
  10. 10.💡 An LED is joined to a 5 V battery through a 470 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) does not light (b) may burn out (c) lights up
  11. 11.🔺 A current of 25 mA flows when 12.5 V is joined across a resistor. What is its resistance (in ohms)?
  12. 12.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V × I (c) P = V + I (d) P = I ÷ V
  13. 13.True or false: to leave fridge door open wastes electricity. (a) True (b) False
  14. 14.📏 In the water-pipe picture of a circuit, voltage is like … (a) the pipe colour (b) the tap handle (c) the water tank lid (d) the water pressure
  15. 15.What does a capacitor do? (a) senses how bright it is (b) limits the current (c) makes things spin (d) stores a little charge
  16. 16.⚡ A 0.6 W device works on 6 V. What current does it take (in amperes)? =
  17. 17.🧮 A 6 V battery is joined to 4 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
  18. 18.⚡ A device works on 24 V and takes 0.1 A. What is its power (in watts)? =
  19. 19.🧾 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?
  20. 20.🔺 A 5 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  21. 21.🧮 A 33 Ω resistor is joined in series with two equal 40 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  22. 22.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 10 hours. How many watt-hours (Wh) are saved?
  23. 23.🌈 A resistor has the colour bands green, grey, orange. What is its value (in ohms)?
  24. 24.🌈 A resistor has the colour bands white, green, orange. What is its value in kilo-ohms (kΩ)? =
  25. 25.True or false: the ammeter is joined in series. (a) True (b) False
  26. 26.🔺 A current of 0.5 A flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  27. 27.🔺 A current of 0.2 A flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
  28. 28.🧾 A 200 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
  29. 29.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 5 % (d) 25 %
  30. 30.🔺 A current of 25 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.📏 How many milliamperes (mA) make 1 ampere? (a) 60 (b) 10 (c) 1000 (d) 100
  32. 32.🔍 Which is the odd one out? (a) leave the TV on standby (b) use old filament bulbs (c) iron one shirt at a time (d) use LED lamps
  33. 33.🌈 In the resistor colour code, which number does black stand for?
  34. 34.🔺 A current of 2 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 ampere (c) 1 kilowatt-hour (kWh) (d) 1 volt
  36. 36.⚡ A device works on 3 V and takes 0.1 A. What is its power (in watts)? =
  37. 37.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
  38. 38.🧩 A capacitor in a circuit can … (a) measure heat (b) store charge briefly (c) spin a wheel (d) make light
  39. 39.📏 How many ohms (Ω) is 1.3 kΩ?
  40. 40.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 50 Ω resistor? (a) green-black-brown (b) blue-black-black (c) blue-green-black (d) green-black-black

Answer key

  1. 20
  2. 7.5
  3. 8
  4. 412
  5. 5
  6. cathode (−)
  7. 4.5
  8. 120
  9. voltmeter
  10. lights up
  11. 500
  12. P = V × I
  13. True
  14. the water pressure
  15. stores a little charge
  16. 0.1
  17. 0.5
  18. 2.4
  19. 126
  20. 1
  21. 53
  22. 850
  23. 58000
  24. 95
  25. True
  26. 20
  27. 20
  28. 1
  29. 5 %
  30. 5.5
  31. 1000
  32. use LED lamps
  33. 0
  34. 40
  35. 1 kilowatt-hour (kWh)
  36. 0.3
  37. 2300
  38. store charge briefly
  39. 1300
  40. green-black-black

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