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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 716 · 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.📏 How many milliamperes (mA) is 0.63 A?
  2. 2.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = V × I (d) P = I ÷ V
  3. 3.🧮 Resistors of 100 Ω, 330 Ω, 47 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
  4. 4.🔺 A current of 40 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  5. 5.📏 Which unit measures power? (a) ohm (Ω) (b) watt (W) (c) volt (V) (d) ampere (A)
  6. 6.🧮 Resistors of 22 Ω, 150 Ω, 100 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
  7. 7.What does a transistor do? (a) senses how hot it is (b) limits the current (c) lets current go one way (d) boosts a small signal
  8. 8.💡 An LED is joined to a 5 V battery through a 1000 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
  9. 9.🌈 A resistor has the colour bands white, grey, black. What is its value (in ohms)?
  10. 10.🌈 In the resistor colour code, which number does brown stand for?
  11. 11.🧩 Which component boosts a small signal? (a) thermistor (b) resistor (c) diode (d) transistor
  12. 12.🔺 A 12 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  13. 13.🧩 Which component has coloured bands? (a) resistor (b) capacitor (c) thermistor (d) potentiometer
  14. 14.Which of these saves electricity? (a) leave the TV on standby (b) leave fridge door open (c) close the fridge quickly (d) run fans in empty rooms
  15. 15.🧮 A 20 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  16. 16.📏 How many milliamperes (mA) is 2.41 A?
  17. 17.📏 How many watts (W) is 4.2 kW?
  18. 18.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 4 V supply. What current flows (in mA)?
  19. 19.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  20. 20.⚡ A device works on 24 V and takes 0.5 A. What is its power (in watts)? =
  21. 21.True or false: a potentiometer smooths a wobbly supply. (a) False (b) True
  22. 22.📏 How many milliamperes (mA) is 3 A?
  23. 23.🔺 A 1 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  24. 24.True or false: a transistor boosts a small signal. (a) False (b) True
  25. 25.📏 How many kilowatts (kW) is 3250 W? =
  26. 26.📏 How many amperes (A) is 1470 mA? =
  27. 27.🔺 An 8.8 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
  28. 28.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  29. 29.🌈 In the resistor colour code, which number does white stand for?
  30. 30.True or false: the push of a cell is measured in volts (V). (a) False (b) True
  31. 31.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  32. 32.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a diode (c) a resistor (d) a buzzer
  33. 33.📏 Which unit measures current? (a) watt (W) (b) volt (V) (c) ohm (Ω) (d) ampere (A)
  34. 34.📏 How many kilowatts (kW) is 2950 W? =
  35. 35.What does a capacitor do? (a) turns a fan or wheels (b) limits the current (c) stores a little charge (d) makes a beeping sound
  36. 36.🧮 Two resistors in parallel give a total that is … (a) always zero (b) more than either one (c) less than either one (d) their sum
  37. 37.True or false: a buzzer makes a beeping sound. (a) False (b) True
  38. 38.🔺 A 0.6 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  39. 39.🔺 A current of 10 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  40. 40.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to make it brighter (c) to change its colour (d) to store charge

Answer key

  1. 630
  2. P = V × I
  3. 524
  4. 8
  5. watt (W)
  6. 602
  7. boosts a small signal
  8. lights up
  9. 98
  10. 1
  11. transistor
  12. 1.5
  13. resistor
  14. close the fridge quickly
  15. 25
  16. 2410
  17. 4200
  18. 20
  19. 10
  20. 12
  21. False
  22. 3000
  23. 10
  24. True
  25. 3.25
  26. 1.47
  27. 40
  28. 345
  29. 9
  30. True
  31. 1
  32. a buzzer
  33. ampere (A)
  34. 2.95
  35. stores a little charge
  36. less than either one
  37. True
  38. 0.2
  39. 2.5
  40. to limit the current

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