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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 383 · 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 5 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  2. 2.🧾 Which lamp gives the same light for the least power? (a) a candle (b) a filament bulb (c) an oil lamp (d) an LED lamp
  3. 3.🔺 A 0.2 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  4. 4.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) False (b) True
  5. 5.📏 How many amperes (A) is 820 mA? =
  6. 6.🔺 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
  7. 7.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V × I (d) P = V ÷ I
  8. 8.🧾 A 500 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
  9. 9.🌈 In the resistor colour code, which number does orange stand for?
  10. 10.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) stays the same (c) gets smaller (d) becomes zero
  11. 11.🔺 A current of 50 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  12. 12.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
  13. 13.🧩 Which component glows using little power? (a) potentiometer (b) LED (c) buzzer (d) fuse
  14. 14.True or false: on an LED, the round-side leg is the cathode (−). (a) False (b) True
  15. 15.🔺 A current of 50 mA flows when 12.5 V is joined across a resistor. What is its resistance (in ohms)?
  16. 16.🔺 A current of 20 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.💡 A red LED uses 2 V and should get 20 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
  18. 18.📏 How many ohms (Ω) is 4.5 kΩ?
  19. 19.🔺 A current of 50 mA flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
  20. 20.🧮 Resistors of 50 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
  21. 21.True or false: a capacitor has coloured bands. (a) False (b) True
  22. 22.🧮 Resistors of 470 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
  23. 23.⚡ Power tells us … (a) the colour of light (b) the size of a cell (c) energy used each second (d) the length of a wire
  24. 24.💡 Does it save or waste electricity to switch off empty rooms? (a) wastes electricity (b) saves electricity
  25. 25.🧩 Which component lets current go one way? (a) LDR (b) diode (c) buzzer (d) LED
  26. 26.🔺 A 4 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  27. 27.🌈 In the resistor colour code, which number does white stand for?
  28. 28.True or false: on an LED, the shorter leg is the anode (+). (a) True (b) False
  29. 29.🌈 A resistor has the colour bands orange, grey, orange. What is its value in kilo-ohms (kΩ)? =
  30. 30.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) zero (c) stay the same (d) bigger
  31. 31.🔺 A current of 10 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  32. 32.⚡ A device works on 24 V and takes 1.5 A. What is its power (in watts)? =
  33. 33.True or false: a buzzer beeps for an alarm. (a) True (b) False
  34. 34.⚡ A 2.25 W device works on 1.5 V. What current does it take (in amperes)? =
  35. 35.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
  36. 36.Which of these is measured in watts (W)? (a) how much a part resists (b) energy used each second (c) voltage (d) the push of a cell
  37. 37.True or false: to set the AC to 24 °C wastes electricity. (a) False (b) True
  38. 38.🧮 Resistors of 68 Ω and 220 Ω are joined in series. What is the total resistance (in ohms)?
  39. 39.⚡ A device works on 12 V and takes 1 A. What is its power (in watts)? =
  40. 40.True or false: a transistor smooths a wobbly supply. (a) False (b) True

Answer key

  1. 0.5
  2. an LED lamp
  3. 0.1
  4. True
  5. 0.82
  6. I = V ÷ R
  7. P = V × I
  8. 2.5
  9. 3
  10. gets smaller
  11. 23.5
  12. 460
  13. LED
  14. False
  15. 250
  16. 2.4
  17. 500
  18. 4500
  19. 150
  20. 100
  21. False
  22. 538
  23. energy used each second
  24. saves electricity
  25. diode
  26. 0.2
  27. 9
  28. False
  29. 38
  30. bigger
  31. 3
  32. 36
  33. True
  34. 1.5
  35. voltmeter
  36. energy used each second
  37. False
  38. 288
  39. 12
  40. False

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