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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 422 · 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 part changes electrical energy into sound? (a) a capacitor (b) a buzzer (c) a resistor (d) a diode
  2. 2.🧮 A 1.4 V battery is joined to 2 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
  3. 3.🌈 In the resistor colour code, which number does green stand for?
  4. 4.💡 An LED is joined to a 5 V battery with no 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
  5. 5.🧮 Three equal 75 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  6. 6.🧮 Two resistors in parallel give a total that is … (a) always zero (b) more than either one (c) less than either one (d) their sum
  7. 7.🔺 A 3.3 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
  8. 8.⚡ A 4.8 W device works on 24 V. What current does it take (in amperes)? =
  9. 9.🧮 Resistors of 100 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
  10. 10.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) stay the same (c) zero (d) bigger
  11. 11.🔺 A current of 10 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  12. 12.🔍 Which is the odd one out? (a) close the fridge quickly (b) use LED lamps (c) switch off empty rooms (d) leave fridge door open
  13. 13.🔺 A current of 50 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.🌈 A resistor has the colour bands violet, brown, orange. What is its value in kilo-ohms (kΩ)? =
  15. 15.🌈 Which band is read first on a resistor? (a) any band (b) the widest gap (c) the one nearest an end (d) the gold band
  16. 16.🧮 A 4 V battery is joined to 6 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
  17. 17.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  18. 18.⚡ A 4.5 W device works on 3 V. What current does it take (in amperes)? =
  19. 19.🔺 A 16.5 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
  20. 20.🔺 A 12 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  21. 21.🌈 In the resistor colour code, which number does red stand for?
  22. 22.🔺 A current of 50 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.⚡ A device works on 3 V and takes 0.2 A. What is its power (in watts)? =
  24. 24.🔺 A 16 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  25. 25.📏 How many watts (W) is 3.3 kW?
  26. 26.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
  27. 27.⚡ A device works on 24 V and takes 1.5 A. What is its power (in watts)? =
  28. 28.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to change its colour (c) to limit the current (d) to store charge
  29. 29.📏 How many milliamperes (mA) is 0.08 A?
  30. 30.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) stays the same (c) gets smaller (d) gets bigger
  31. 31.📏 How many milliamperes (mA) is 2.41 A?
  32. 32.Which of these is measured in ohms (Ω)? (a) resistance (b) voltage (c) the push of a cell (d) energy used each second
  33. 33.⚡ A 36 W device works on 24 V. What current does it take (in amperes)? =
  34. 34.📏 How many kilo-ohms (kΩ) is 3700 Ω? =
  35. 35.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = I ÷ V (c) P = V + I (d) P = V × I
  36. 36.True or false: voltage is measured in volts (V). (a) False (b) True
  37. 37.Which of these wastes electricity? (a) use old filament bulbs (b) use daylight to read (c) close the fridge quickly (d) unplug idle chargers
  38. 38.📏 How many kilo-ohms (kΩ) is 4400 Ω? =
  39. 39.🧮 Five equal 125 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  40. 40.🔺 A current of 20 mA flows when 4.4 V is joined across a resistor. What is its resistance (in ohms)?

Answer key

  1. a buzzer
  2. 0.1
  3. 5
  4. may burn out
  5. 25
  6. less than either one
  7. 10
  8. 0.2
  9. 168
  10. bigger
  11. 2
  12. leave fridge door open
  13. 12.5
  14. 71
  15. the one nearest an end
  16. 0.25
  17. cathode (−)
  18. 1.5
  19. 50
  20. 3
  21. 2
  22. 6
  23. 0.6
  24. 40
  25. 3300
  26. ammeter
  27. 36
  28. to limit the current
  29. 80
  30. gets smaller
  31. 2410
  32. resistance
  33. 1.5
  34. 3.7
  35. P = V × I
  36. True
  37. use old filament bulbs
  38. 4.4
  39. 25
  40. 220

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