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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 157 · 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 0.4 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  2. 2.📏 How many amperes (A) is 890 mA? =
  3. 3.💡 An LED is joined to a 5 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) lights up (b) does not light (c) may burn out
  4. 4.💡 Does it save or waste electricity to close the fridge quickly? (a) saves electricity (b) wastes electricity
  5. 5.🔺 A current of 1.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.🔺 A current of 25 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  7. 7.🔺 A current of 0.1 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  8. 8.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
  9. 9.🧮 A 1 V battery is joined to 3 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
  10. 10.🔺 A current of 25 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  11. 11.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
  12. 12.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V + I (c) P = V ÷ I (d) P = V × I
  13. 13.True or false: to switch off empty rooms saves electricity. (a) True (b) False
  14. 14.🔍 Which is the odd one out? (a) use LED lamps (b) leave the TV on standby (c) iron one shirt at a time (d) run fans in empty rooms
  15. 15.Which of these is measured in watts (W)? (a) current (b) power (c) the push of a cell (d) voltage
  16. 16.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 5 % (d) 25 %
  17. 17.🧮 Four equal 80 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  18. 18.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
  19. 19.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 5 V supply. What current flows (in mA)?
  20. 20.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = V + I (c) R = I ÷ V (d) R = V ÷ I
  21. 21.🔺 A 2 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  22. 22.⚡ A 0.9 W device works on 9 V. What current does it take (in amperes)? =
  23. 23.🧮 Three equal 300 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  24. 24.🔺 A 13.2 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
  25. 25.📏 How many milliamperes (mA) is 0.11 A?
  26. 26.💡 Does it save or waste electricity to use LED lamps? (a) wastes electricity (b) saves electricity
  27. 27.What does a motor do? (a) makes a beeping sound (b) senses how hot it is (c) senses how bright it is (d) turns a fan or wheels
  28. 28.🔺 A current of 2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  29. 29.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
  30. 30.🌈 In the resistor colour code, which number does white stand for?
  31. 31.🔺 A 4 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  32. 32.🔺 A current of 0.1 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  33. 33.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
  34. 34.🧩 A capacitor in a circuit can … (a) store charge briefly (b) spin a wheel (c) measure heat (d) make light
  35. 35.💡 A red LED uses 2 V and should get 20 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
  36. 36.⚡ A device works on 3 V and takes 0.2 A. What is its power (in watts)? =
  37. 37.🌈 A resistor has the colour bands white, violet, brown. What is its value (in ohms)?
  38. 38.💡 An LED is joined to a 3 V battery through a 330 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) lights up (b) does not light (c) may burn out
  39. 39.🧾 A 200 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
  40. 40.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?

Answer key

  1. 0.1
  2. 0.89
  3. may burn out
  4. saves electricity
  5. 7.5
  6. 5
  7. 1
  8. False
  9. 0.2
  10. 11.75
  11. True
  12. P = V × I
  13. True
  14. use LED lamps
  15. power
  16. 5 %
  17. 20
  18. ammeter
  19. 15
  20. R = V ÷ I
  21. 0.25
  22. 0.1
  23. 100
  24. 40
  25. 110
  26. saves electricity
  27. turns a fan or wheels
  28. 6
  29. 920
  30. 9
  31. 10
  32. 20
  33. False
  34. store charge briefly
  35. 200
  36. 0.6
  37. 970
  38. lights up
  39. 1.6
  40. 115

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