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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 992 · 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 250 Ω resistor. What is the voltage across it (in volts)? =
  2. 2.🔺 A current of 1.5 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  3. 3.🔺 A current of 3 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  4. 4.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = R ÷ V (c) I = V × R (d) I = V ÷ R
  5. 5.🌈 A resistor has the colour bands yellow, white, yellow. What is its value in kilo-ohms (kΩ)? =
  6. 6.🌈 A resistor has the colour bands grey, violet, red. What is its value in kilo-ohms (kΩ)? =
  7. 7.🔺 A current of 20 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  8. 8.What does a potentiometer do? (a) has coloured bands (b) blows if current is high (c) beeps for an alarm (d) is a resistance knob
  9. 9.🧩 Which part changes electrical energy into sound? (a) a buzzer (b) a capacitor (c) a resistor (d) a diode
  10. 10.🔺 A 0.4 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  11. 11.💡 A red LED uses 2 V and should get 25 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
  12. 12.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) smaller (c) bigger (d) stay the same
  13. 13.Which of these saves electricity? (a) leave the TV on standby (b) iron one shirt at a time (c) use old filament bulbs (d) use LED lamps
  14. 14.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  15. 15.⚡ A 24 W device works on 24 V. What current does it take (in amperes)? =
  16. 16.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I × R (c) V = R ÷ I (d) V = I + R
  17. 17.💡 Does it save or waste electricity to run fans in empty rooms? (a) wastes electricity (b) saves electricity
  18. 18.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 6 V supply. What current flows (in mA)?
  19. 19.💡 An LED is joined to a 9 V battery through a 470 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) does not light (b) may burn out (c) lights up
  20. 20.🔺 A 10 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  21. 21.🌈 A resistor has the colour bands yellow, black, black. What is its value (in ohms)?
  22. 22.True or false: to leave fridge door open wastes electricity. (a) False (b) True
  23. 23.🧾 A 200 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
  24. 24.🔺 A current of 50 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  25. 25.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  26. 26.🧩 A capacitor in a circuit can … (a) make light (b) measure heat (c) spin a wheel (d) store charge briefly
  27. 27.What does a motor do? (a) makes things spin (b) senses how hot it is (c) limits the current (d) boosts a small signal
  28. 28.Which of these saves electricity? (a) leave the TV on standby (b) run fans in empty rooms (c) set the AC to 24 °C (d) iron one shirt at a time
  29. 29.📏 Which unit measures power? (a) ampere (A) (b) ohm (Ω) (c) watt (W) (d) volt (V)
  30. 30.📏 In the water-pipe picture of a circuit, voltage is like … (a) the pipe colour (b) the water tank lid (c) the water pressure (d) the tap handle
  31. 31.🧮 Five equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  32. 32.True or false: a resistor has coloured bands. (a) True (b) False
  33. 33.💡 Does it save or waste electricity to switch off empty rooms? (a) wastes electricity (b) saves electricity
  34. 34.True or false: the flow of charge is measured in amperes (A). (a) False (b) True
  35. 35.💡 Does it save or waste electricity to use daylight to read? (a) saves electricity (b) wastes electricity
  36. 36.🌈 A resistor has the colour bands red, blue, yellow. What is its value in kilo-ohms (kΩ)? =
  37. 37.🔺 A 60 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  38. 38.🔺 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
  39. 39.⚡ A device works on 6 V and takes 1.5 A. What is its power (in watts)? =
  40. 40.True or false: a resistor senses how bright it is. (a) False (b) True

Answer key

  1. 12.5
  2. 22.5
  3. 15
  4. I = V ÷ R
  5. 490
  6. 8.7
  7. 10
  8. is a resistance knob
  9. a buzzer
  10. 0.2
  11. 160
  12. bigger
  13. use LED lamps
  14. 165
  15. 1
  16. V = I × R
  17. wastes electricity
  18. 20
  19. does not light
  20. 20
  21. 40
  22. True
  23. 1.2
  24. 100
  25. cathode (−)
  26. store charge briefly
  27. makes things spin
  28. set the AC to 24 °C
  29. watt (W)
  30. the water pressure
  31. 20
  32. True
  33. saves electricity
  34. True
  35. saves electricity
  36. 260
  37. 3
  38. R = V ÷ I
  39. 9
  40. False

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