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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 832 · 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 current of 50 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  2. 2.🔺 A 5 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  3. 3.🔺 A 0.6 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  4. 4.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  5. 5.🧮 Two resistors in parallel give a total that is … (a) always zero (b) more than either one (c) their sum (d) less than either one
  6. 6.🧮 A 50 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)?
  7. 7.🔺 A current of 20 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  8. 8.💡 Does it save or waste electricity to set the AC to 24 °C? (a) wastes electricity (b) saves electricity
  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: a motor turns a fan or wheels. (a) False (b) True
  11. 11.📏 How many kilowatts (kW) is 300 W? =
  12. 12.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  13. 13.🔺 A current of 0.2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 10 hours. How many watt-hours (Wh) are saved?
  15. 15.🔺 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
  16. 16.What does a diode do? (a) lets current go one way (b) blows if current is high (c) smooths a wobbly supply (d) limits the current
  17. 17.🔺 A current of 0.25 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  18. 18.💡 A red LED uses 2 V and should get 25 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
  19. 19.🔺 A 12 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  20. 20.Which of these wastes electricity? (a) use daylight to read (b) leave the TV on standby (c) switch off empty rooms (d) set the AC to 24 °C
  21. 21.🔺 A current of 40 mA flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  22. 22.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
  23. 23.🧮 A 9 V battery is joined to 3 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
  24. 24.🔺 A 4.8 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  25. 25.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  26. 26.True or false: to leave the TV on standby wastes electricity. (a) True (b) False
  27. 27.🧮 A 10 Ω resistor is joined in series with two equal 330 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  28. 28.🌈 A resistor has the colour bands green, black, orange. What is its value (in ohms)?
  29. 29.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) gets smaller (c) stays the same (d) becomes zero
  30. 30.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
  31. 31.Which of these is measured in watts (W)? (a) current (b) voltage (c) the push of a cell (d) energy used each second
  32. 32.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a resistor (c) a diode (d) a buzzer
  33. 33.True or false: the voltmeter is joined in series. (a) False (b) True
  34. 34.🔺 A current of 2 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.📏 How many kilowatts (kW) is 2550 W? =
  36. 36.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 10 (b) 1024 (c) 1000 (d) 100
  37. 37.🧮 Three equal 75 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  38. 38.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V × I (c) P = V ÷ I (d) P = V + I
  39. 39.🔺 A current of 25 mA flows when 3.75 V is joined across a resistor. What is its resistance (in ohms)?
  40. 40.True or false: the flow of charge is measured in ohms (Ω). (a) True (b) False

Answer key

  1. 15
  2. 10
  3. 0.2
  4. anode (+)
  5. less than either one
  6. 75
  7. 100
  8. saves electricity
  9. to limit the current
  10. True
  11. 0.3
  12. 100
  13. 2
  14. 510
  15. V = I × R
  16. lets current go one way
  17. 1
  18. 400
  19. 1
  20. leave the TV on standby
  21. 150
  22. 230
  23. 1
  24. 40
  25. 20
  26. True
  27. 175
  28. 50000
  29. gets smaller
  30. True
  31. energy used each second
  32. a buzzer
  33. False
  34. 12
  35. 2.55
  36. 1000
  37. 25
  38. P = V × I
  39. 150
  40. False

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