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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 461 · 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.

NameDateTime takenScore ___ / 40
  1. 1.⚡ A 9 W device works on 6 V. What current does it take (in amperes)? =
  2. 2.True or false: to leave fridge door open wastes electricity. (a) True (b) False
  3. 3.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 54000 Ω resistor? (a) green-yellow-red (b) yellow-green-orange (c) green-yellow-orange (d) green-yellow-yellow
  4. 4.🔺 An 8 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  5. 5.📏 Which unit measures how much a part resists? (a) watt (W) (b) ohm (Ω) (c) ampere (A) (d) volt (V)
  6. 6.🧮 A 1.7 V battery is joined to 5 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
  7. 7.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  8. 8.🔺 A 0.4 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  9. 9.🔺 A current of 40 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  10. 10.🧩 Which part changes electrical energy into sound? (a) a diode (b) a buzzer (c) a capacitor (d) a resistor
  11. 11.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) more than either one (c) always zero (d) their sum
  12. 12.📏 Which unit measures current? (a) ampere (A) (b) watt (W) (c) volt (V) (d) ohm (Ω)
  13. 13.🧾 A 50 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
  14. 14.🔺 A current of 50 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.🔺 A current of 20 mA flows when 6.6 V is joined across a resistor. What is its resistance (in ohms)?
  16. 16.🔺 A current of 2.5 A flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  17. 17.What does a fuse do? (a) senses how hot it is (b) has coloured bands (c) makes a beeping sound (d) blows if current is high
  18. 18.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  19. 19.🧩 A capacitor in a circuit can … (a) store charge briefly (b) spin a wheel (c) measure heat (d) make light
  20. 20.🧮 A 0.8 V battery is joined to 2 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
  21. 21.🧮 Three equal 60 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  22. 22.🧮 Resistors of 47 Ω, 470 Ω, 470 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
  23. 23.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 57 Ω resistor? (a) green-violet-brown (b) blue-violet-black (c) violet-green-black (d) green-violet-black
  24. 24.True or false: to switch off empty rooms saves electricity. (a) False (b) True
  25. 25.🧮 Five equal 25 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  26. 26.True or false: resistance is measured in ohms (Ω). (a) False (b) True
  27. 27.🧮 Three equal 300 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  28. 28.⚡ A 0.3 W device works on 1.5 V. What current does it take (in amperes)? =
  29. 29.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
  30. 30.🌈 A resistor has the colour bands orange, red, yellow. What is its value in kilo-ohms (kΩ)? =
  31. 31.💡 Does it save or waste electricity to set the AC to 24 °C? (a) saves electricity (b) wastes electricity
  32. 32.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V × I (c) P = I ÷ V (d) P = V + I
  33. 33.🌈 A resistor has the colour bands yellow, black, black. What is its value (in ohms)?
  34. 34.True or false: to close the fridge quickly saves electricity. (a) False (b) True
  35. 35.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  36. 36.🔺 A current of 2.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  37. 37.🔺 In the V-I-R triangle, how do we find R? (a) R = V ÷ I (b) R = V + I (c) R = V × I (d) R = I ÷ V
  38. 38.⚡ A device works on 6 V and takes 1 A. What is its power (in watts)? =
  39. 39.⚡ A 0.6 W device works on 3 V. What current does it take (in amperes)? =
  40. 40.🧩 Which component limits the current? (a) potentiometer (b) motor (c) resistor (d) fuse

Answer key

  1. 1.5
  2. True
  3. green-yellow-orange
  4. 1
  5. ohm (Ω)
  6. 0.1
  7. 100
  8. 0.1
  9. 12
  10. a buzzer
  11. less than either one
  12. ampere (A)
  13. 0.2
  14. 10
  15. 330
  16. 2
  17. blows if current is high
  18. cathode (−)
  19. store charge briefly
  20. 0.2
  21. 20
  22. 997
  23. green-violet-black
  24. True
  25. 5
  26. True
  27. 100
  28. 0.2
  29. ammeter
  30. 320
  31. saves electricity
  32. P = V × I
  33. 40
  34. True
  35. 500
  36. 50
  37. R = V ÷ I
  38. 6
  39. 0.2
  40. resistor

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