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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 267 · 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 resistor has the colour bands white, orange, orange. What is its value in kilo-ohms (kΩ)? =
  2. 2.True or false: to use LED lamps saves electricity. (a) False (b) True
  3. 3.🔺 A 6.25 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
  4. 4.🔺 A current of 10 mA flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  5. 5.🧮 Resistors of 22 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
  6. 6.🌈 A resistor has the colour bands red, yellow, orange. What is its value in kilo-ohms (kΩ)? =
  7. 7.🌈 A resistor has the colour bands violet, red, red. What is its value in kilo-ohms (kΩ)? =
  8. 8.🌈 A resistor has the colour bands blue, violet, red. What is its value (in ohms)?
  9. 9.True or false: on an LED, the longer leg is the anode (+). (a) True (b) False
  10. 10.🔺 A current of 0.25 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  11. 11.🔺 A current of 10 mA flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
  12. 12.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 230 Ω resistor? (a) red-orange-brown (b) orange-red-brown (c) red-orange-black (d) red-orange-red
  13. 13.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 8 hours. How many watt-hours (Wh) are saved?
  14. 14.🧩 A capacitor in a circuit can … (a) measure heat (b) spin a wheel (c) store charge briefly (d) make light
  15. 15.📏 How many kilo-ohms (kΩ) is 8400 Ω? =
  16. 16.🔺 A current of 2.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
  18. 18.True or false: to use LED lamps wastes electricity. (a) False (b) True
  19. 19.🔺 An 18 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  20. 20.💡 Why does an LED need a resistor in series? (a) to store charge (b) to limit the current (c) to change its colour (d) to make it brighter
  21. 21.True or false: the voltmeter is joined in series. (a) False (b) True
  22. 22.🧩 Which component has coloured bands? (a) potentiometer (b) transistor (c) diode (d) resistor
  23. 23.True or false: power is measured in watts (W). (a) True (b) False
  24. 24.🔺 A current of 1.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.🧩 Which component blows if current is high? (a) LDR (b) buzzer (c) fuse (d) diode
  26. 26.⚡ A device works on 1.5 V and takes 2 A. What is its power (in watts)? =
  27. 27.📏 How many kilowatts (kW) is 1200 W? =
  28. 28.🔺 A current of 50 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  29. 29.🔺 A current of 40 mA flows when 8 V is joined across a resistor. What is its resistance (in ohms)?
  30. 30.📏 How many ohms (Ω) is 7.4 kΩ?
  31. 31.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  32. 32.💡 Does it save or waste electricity to switch off empty rooms? (a) saves electricity (b) wastes electricity
  33. 33.🔺 In the V-I-R triangle, how do we find R? (a) R = V ÷ I (b) R = I ÷ V (c) R = V × I (d) R = V + I
  34. 34.🔺 A current of 0.25 A flows when 1.25 V is joined across a resistor. What is its resistance (in ohms)?
  35. 35.🔺 A current of 0.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.⚡ A device works on 9 V and takes 3 A. What is its power (in watts)? =
  37. 37.⚡ A device works on 6 V and takes 0.2 A. What is its power (in watts)? =
  38. 38.⚡ A device works on 9 V and takes 0.5 A. What is its power (in watts)? =
  39. 39.🔺 A current of 1.5 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  40. 40.⚡ A 1.5 W device works on 6 V. What current does it take (in amperes)? =

Answer key

  1. 93
  2. True
  3. 25
  4. 300
  5. 44
  6. 24
  7. 7.2
  8. 6700
  9. True
  10. 2
  11. 400
  12. red-orange-brown
  13. 680
  14. store charge briefly
  15. 8.4
  16. 25
  17. 115
  18. False
  19. 3
  20. to limit the current
  21. False
  22. resistor
  23. True
  24. 7.5
  25. fuse
  26. 3
  27. 1.2
  28. 20
  29. 200
  30. 7400
  31. 1.2
  32. saves electricity
  33. R = V ÷ I
  34. 5
  35. 5
  36. 27
  37. 1.2
  38. 4.5
  39. 2
  40. 0.25

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