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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 425 · 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 22.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  2. 2.🔺 A current of 1.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  3. 3.⚡ A device works on 9 V and takes 0.1 A. What is its power (in watts)? =
  4. 4.🧮 A 10 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)?
  5. 5.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 50 % (c) 25 % (d) 0 %
  6. 6.💡 Does it save or waste electricity to leave the TV on standby? (a) saves electricity (b) wastes electricity
  7. 7.⚡ Power tells us … (a) the length of a wire (b) the size of a cell (c) energy used each second (d) the colour of light
  8. 8.🔺 A 12.5 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  9. 9.🧮 A 50 Ω resistor is joined in series with two equal 220 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  10. 10.⚡ A 2.4 W device works on 24 V. What current does it take (in amperes)? =
  11. 11.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it does not light (c) it changes colour (d) it makes a sound
  12. 12.🔺 In the V-I-R triangle, how do we find V? (a) V = I × R (b) V = R ÷ I (c) V = I + R (d) V = I ÷ R
  13. 13.📏 How many milliamperes (mA) is 1.91 A?
  14. 14.True or false: the voltmeter is joined across a part. (a) False (b) True
  15. 15.🧮 An 11 V battery is joined to 3 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
  16. 16.🌈 A resistor has the colour bands yellow, orange, red. What is its value (in ohms)?
  17. 17.🔺 A current of 50 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  18. 18.🌈 In the resistor colour code, which number does grey stand for?
  19. 19.🌈 A resistor has the colour bands grey, black, black. What is its value (in ohms)?
  20. 20.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) bigger (c) smaller (d) stay the same
  21. 21.💡 What does LED stand for? (a) large electric dial (b) light-emitting diode (c) light energy dial (d) low energy device
  22. 22.📏 How many kilo-ohms (kΩ) is 9200 Ω? =
  23. 23.Which of these is measured in watts (W)? (a) the push of a cell (b) energy used each second (c) current (d) how much a part resists
  24. 24.🔺 A current of 10 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.🔺 A current of 0.25 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  26. 26.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 89000 Ω resistor? (a) white-grey-orange (b) grey-white-orange (c) grey-white-red (d) grey-white-yellow
  27. 27.🔺 A current of 2 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  28. 28.💡 An LED is joined to a 3 V battery through a 1000 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) may burn out (b) does not light (c) lights up
  29. 29.True or false: on an LED, the round-side leg is the anode (+). (a) True (b) False
  30. 30.🔺 A current of 2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.💡 An LED is joined to a 9 V battery through a 470 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) may burn out (c) lights up
  32. 32.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
  33. 33.What does a fuse do? (a) turns a fan or wheels (b) stores a little charge (c) limits the current (d) blows if current is high
  34. 34.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
  35. 35.True or false: to iron one shirt at a time wastes electricity. (a) False (b) True
  36. 36.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 4 hours. How many watt-hours (Wh) are saved?
  37. 37.🔺 A current of 2.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  38. 38.🔺 A 60 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  39. 39.⚡ A 2.25 W device works on 9 V. What current does it take (in amperes)? =
  40. 40.💡 A red LED uses 2 V and should get 25 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?

Answer key

  1. 1.5
  2. 3
  3. 0.9
  4. 35
  5. 5 %
  6. wastes electricity
  7. energy used each second
  8. 25
  9. 160
  10. 0.1
  11. it does not light
  12. V = I × R
  13. 1910
  14. True
  15. 1
  16. 4300
  17. 20
  18. 8
  19. 80
  20. bigger
  21. light-emitting diode
  22. 9.2
  23. energy used each second
  24. 1.5
  25. 5
  26. grey-white-orange
  27. 24
  28. does not light
  29. True
  30. 8
  31. lights up
  32. 2300
  33. blows if current is high
  34. 1840
  35. True
  36. 136
  37. 5
  38. 3
  39. 0.25
  40. 120

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