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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 705 · 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.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V + I (c) P = V ÷ I (d) P = V × I
  2. 2.💡 Does it save or waste electricity to run fans in empty rooms? (a) wastes electricity (b) saves electricity
  3. 3.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets smaller (c) gets bigger (d) stays the same
  4. 4.🔺 A 4 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  5. 5.🔺 A 30 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  6. 6.🌈 A resistor has the colour bands violet, red, yellow. What is its value in kilo-ohms (kΩ)? =
  7. 7.Which of these is measured in watts (W)? (a) resistance (b) the flow of charge (c) the push of a cell (d) energy used each second
  8. 8.🔍 Which is the odd one out? (a) use old filament bulbs (b) leave fridge door open (c) run fans in empty rooms (d) set the AC to 24 °C
  9. 9.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V + I (c) R = V × I (d) R = V ÷ I
  10. 10.🔺 A 1.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  11. 11.📏 How many kilo-ohms (kΩ) is 1400 Ω? =
  12. 12.What does a diode do? (a) beeps for an alarm (b) turns a fan or wheels (c) lets current go one way (d) makes things spin
  13. 13.🔺 A current of 0.1 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a buzzer (c) a capacitor (d) a diode
  15. 15.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  16. 16.🧩 A capacitor in a circuit can … (a) make light (b) measure heat (c) store charge briefly (d) spin a wheel
  17. 17.🔺 A current of 50 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  18. 18.🧮 A 5 V battery is joined to 5 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
  19. 19.🔺 A current of 2.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.Which of these wastes electricity? (a) close the fridge quickly (b) switch off empty rooms (c) use old filament bulbs (d) use LED lamps
  21. 21.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  22. 22.📏 Which unit measures the push of a cell? (a) watt (W) (b) volt (V) (c) ampere (A) (d) ohm (Ω)
  23. 23.💡 An LED is joined to a 5 V battery through a 330 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) does not light (b) may burn out (c) lights up
  24. 24.🔺 A current of 1.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.🧮 A 22 Ω resistor is joined in series with two equal 40 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  26. 26.🌈 A resistor has the colour bands violet, black, orange. What is its value (in ohms)?
  27. 27.🔺 A current of 0.25 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  28. 28.🔺 A 2.4 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  29. 29.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it lights brighter (c) it changes colour (d) it does not light
  30. 30.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 4 V supply. What current flows (in mA)?
  31. 31.💡 What does LED stand for? (a) large electric dial (b) light energy dial (c) low energy device (d) light-emitting diode
  32. 32.Which of these wastes electricity? (a) set the AC to 24 °C (b) unplug idle chargers (c) use LED lamps (d) run fans in empty rooms
  33. 33.🔺 A current of 20 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  34. 34.⚡ A device works on 5 V and takes 0.5 A. What is its power (in watts)? =
  35. 35.True or false: a fuse smooths a wobbly supply. (a) False (b) True
  36. 36.🧮 Three equal 150 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  37. 37.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  38. 38.⚡ A 1.5 W device works on 3 V. What current does it take (in amperes)? =
  39. 39.🔺 A current of 2.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  40. 40.True or false: a capacitor smooths a wobbly supply. (a) False (b) True

Answer key

  1. P = V × I
  2. wastes electricity
  3. gets smaller
  4. 40
  5. 2
  6. 720
  7. energy used each second
  8. set the AC to 24 °C
  9. R = V ÷ I
  10. 10
  11. 1.4
  12. lets current go one way
  13. 0.8
  14. a buzzer
  15. 345
  16. store charge briefly
  17. 15
  18. 0.5
  19. 12.5
  20. use old filament bulbs
  21. 80
  22. volt (V)
  23. does not light
  24. 9
  25. 42
  26. 70000
  27. 3
  28. 20
  29. it does not light
  30. 10
  31. light-emitting diode
  32. run fans in empty rooms
  33. 100
  34. 2.5
  35. False
  36. 50
  37. 1.2
  38. 0.5
  39. 7.5
  40. True

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