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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 834 · 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.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) zero (c) bigger (d) stay the same
  2. 2.🔺 A current of 20 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  3. 3.🔺 A current of 0.5 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
  4. 4.💡 Why does an LED need a resistor in series? (a) to store charge (b) to make it brighter (c) to change its colour (d) to limit the current
  5. 5.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) their sum (c) always zero (d) less than either one
  6. 6.🔺 A current of 25 mA flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
  7. 7.🔺 A 0.75 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  8. 8.💡 A red LED uses 2 V and should get 20 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  9. 9.🔺 A current of 0.1 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  10. 10.📏 Which unit measures voltage? (a) watt (W) (b) ampere (A) (c) ohm (Ω) (d) volt (V)
  11. 11.📏 In the water-pipe picture of a circuit, resistance is like … (a) a bigger tank (b) the water pressure (c) a narrow pipe (d) the flow of water
  12. 12.🔺 A 0.3 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  13. 13.🧩 Which part changes electrical energy into sound? (a) a buzzer (b) a capacitor (c) a resistor (d) a diode
  14. 14.🧾 One “unit” on an electricity bill is … (a) 1 kilowatt-hour (kWh) (b) 1 watt (c) 1 ampere (d) 1 volt
  15. 15.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  16. 16.🔺 A current of 25 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
  18. 18.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 10 (b) 100 (c) 1024 (d) 1000
  19. 19.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  20. 20.🔺 A current of 1 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  21. 21.⚡ A 4.8 W device works on 24 V. What current does it take (in amperes)? =
  22. 22.🔺 A current of 0.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.🔺 A current of 2.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  24. 24.📏 In the water-pipe picture of a circuit, voltage is like … (a) the tap handle (b) the water pressure (c) the water tank lid (d) the pipe colour
  25. 25.🔺 A current of 20 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  26. 26.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V + R (c) I = R ÷ V (d) I = V ÷ R
  27. 27.🔺 A current of 25 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  28. 28.🔺 A current of 2.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  29. 29.🔺 A current of 20 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  30. 30.🔺 A current of 3 A flows when 60 V is joined across a resistor. What is its resistance (in ohms)?
  31. 31.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
  32. 32.True or false: to use daylight to read wastes electricity. (a) False (b) True
  33. 33.Which of these is measured in amperes (A)? (a) resistance (b) current (c) energy used each second (d) power
  34. 34.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) stays the same (c) gets bigger (d) gets smaller
  35. 35.🔺 A current of 0.2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.True or false: the push of a cell is measured in ohms (Ω). (a) True (b) False
  37. 37.🔺 A current of 50 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  38. 38.🔺 A 1 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  39. 39.🔺 A current of 10 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  40. 40.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = I ÷ V (d) P = V × I

Answer key

  1. bigger
  2. 6.6
  3. 3
  4. to limit the current
  5. less than either one
  6. 300
  7. 0.25
  8. 150
  9. 20
  10. volt (V)
  11. a narrow pipe
  12. 0.1
  13. a buzzer
  14. 1 kilowatt-hour (kWh)
  15. 235
  16. 5
  17. 230
  18. 1000
  19. 110
  20. 5
  21. 0.2
  22. 2.5
  23. 7.5
  24. the water pressure
  25. 10
  26. I = V ÷ R
  27. 2.5
  28. 5
  29. 500
  30. 20
  31. True
  32. False
  33. current
  34. gets smaller
  35. 2
  36. False
  37. 16.5
  38. 10
  39. 4.7
  40. P = V × I

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