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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 22 · 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.📏 Which unit measures how much a part resists? (a) watt (W) (b) volt (V) (c) ampere (A) (d) ohm (Ω)
  2. 2.🌈 A resistor has the colour bands grey, red, red. What is its value in kilo-ohms (kΩ)? =
  3. 3.🔺 A 4 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  4. 4.What does a resistor do? (a) lets current go one way (b) has coloured bands (c) makes things spin (d) boosts a small signal
  5. 5.🔺 A 0.2 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  6. 6.Which of these is measured in ohms (Ω)? (a) voltage (b) resistance (c) energy used each second (d) the push of a cell
  7. 7.🔺 A 6 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  8. 8.True or false: a capacitor smooths a wobbly supply. (a) True (b) False
  9. 9.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to change its colour (c) to store charge (d) to make it brighter
  10. 10.True or false: the ammeter is joined across a part. (a) False (b) True
  11. 11.⚡ Power tells us … (a) the colour of light (b) energy used each second (c) the length of a wire (d) the size of a cell
  12. 12.⚡ A 1.5 W device works on 1.5 V. What current does it take (in amperes)? =
  13. 13.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V × I (c) P = I ÷ V (d) P = V + I
  14. 14.🔺 A current of 0.1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.True or false: an LED makes things spin. (a) True (b) False
  16. 16.True or false: to iron one shirt at a time wastes electricity. (a) True (b) False
  17. 17.🌈 In the resistor colour code, which number does blue stand for?
  18. 18.📏 How many watts (W) is 1.3 kW?
  19. 19.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
  20. 20.🌈 A resistor has the colour bands orange, red, orange. What is its value in kilo-ohms (kΩ)? =
  21. 21.💡 Does it save or waste electricity to use old filament bulbs? (a) saves electricity (b) wastes electricity
  22. 22.🔺 A current of 0.1 A flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
  23. 23.🔺 A 2.5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
  24. 24.🌈 In the resistor colour code, which number does violet stand for?
  25. 25.⚡ A device works on 6 V and takes 1 A. What is its power (in watts)? =
  26. 26.💡 Does it save or waste electricity to close the fridge quickly? (a) wastes electricity (b) saves electricity
  27. 27.🔺 A current of 50 mA flows when 16.5 V is joined across a resistor. What is its resistance (in ohms)?
  28. 28.🔺 A current of 20 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  29. 29.⚡ A 0.75 W device works on 3 V. What current does it take (in amperes)? =
  30. 30.🔺 A current of 2.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.True or false: the ammeter measures voltage. (a) True (b) False
  32. 32.📏 How many milliamperes (mA) is 0.16 A?
  33. 33.🧮 A 6 V battery is joined to 4 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
  34. 34.🔍 Which is the odd one out? (a) leave the TV on standby (b) use old filament bulbs (c) run fans in empty rooms (d) use daylight to read
  35. 35.⚡ A device works on 12 V and takes 1.5 A. What is its power (in watts)? =
  36. 36.💡 A red LED uses 2 V and should get 10 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
  37. 37.What does an LED do? (a) smooths a wobbly supply (b) senses how hot it is (c) makes a beeping sound (d) glows using little power
  38. 38.🔺 A current of 40 mA flows when 13.2 V is joined across a resistor. What is its resistance (in ohms)?
  39. 39.🔺 A current of 2.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  40. 40.🧮 Resistors of 10 Ω, 470 Ω, 330 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?

Answer key

  1. ohm (Ω)
  2. 8.2
  3. 0.2
  4. has coloured bands
  5. 0.1
  6. resistance
  7. 50
  8. True
  9. to limit the current
  10. False
  11. energy used each second
  12. 1
  13. P = V × I
  14. 2
  15. False
  16. True
  17. 6
  18. 1300
  19. 1840
  20. 32
  21. wastes electricity
  22. 10
  23. 10
  24. 7
  25. 6
  26. saves electricity
  27. 330
  28. 6
  29. 0.25
  30. 7.5
  31. False
  32. 160
  33. 0.5
  34. use daylight to read
  35. 18
  36. 400
  37. glows using little power
  38. 330
  39. 30
  40. 1280

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