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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 935 · 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.True or false: a thermistor senses how hot it is. (a) True (b) False
  2. 2.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = V ÷ R (c) I = V × R (d) I = R ÷ V
  3. 3.🔺 A 4.4 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
  4. 4.🧾 Which lamp gives the same light for the least power? (a) a candle (b) an LED lamp (c) an oil lamp (d) a filament bulb
  5. 5.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V × I (c) P = V ÷ I (d) P = V + I
  6. 6.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to make it brighter (c) to store charge (d) to limit the current
  7. 7.⚡ A 0.15 W device works on 1.5 V. What current does it take (in amperes)? =
  8. 8.🔺 A current of 25 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  9. 9.🧮 Resistors of 10 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
  10. 10.⚡ A device works on 3 V and takes 0.1 A. What is its power (in watts)? =
  11. 11.True or false: to use daylight to read saves electricity. (a) False (b) True
  12. 12.🔺 A current of 0.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  13. 13.⚡ A 4.8 W device works on 24 V. What current does it take (in amperes)? =
  14. 14.🧾 One “unit” on an electricity bill is … (a) 1 kilowatt-hour (kWh) (b) 1 watt (c) 1 volt (d) 1 ampere
  15. 15.True or false: an LED has coloured bands. (a) True (b) False
  16. 16.Which of these is measured in amperes (A)? (a) the push of a cell (b) resistance (c) current (d) power
  17. 17.🌈 In the resistor colour code, which number does yellow stand for?
  18. 18.🌈 A resistor has the colour bands green, black, red. What is its value in kilo-ohms (kΩ)? =
  19. 19.🔺 A current of 10 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.📏 How many ohms (Ω) is 8.8 kΩ?
  21. 21.💡 Does it save or waste electricity to use LED lamps? (a) saves electricity (b) wastes electricity
  22. 22.💡 An LED is joined to a 3 V battery through a 1000 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) may burn out (b) does not light (c) lights up
  23. 23.🔺 A current of 3 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  24. 24.🧩 Which component limits the current? (a) capacitor (b) resistor (c) buzzer (d) LED
  25. 25.🔺 A current of 0.2 A flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
  26. 26.🧾 A 1000 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
  27. 27.🧮 Resistors of 10 Ω, 22 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
  28. 28.🧩 A capacitor in a circuit can … (a) spin a wheel (b) make light (c) store charge briefly (d) measure heat
  29. 29.🌈 A resistor has the colour bands white, blue, red. What is its value in kilo-ohms (kΩ)? =
  30. 30.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.🧮 A 47 Ω resistor is joined in series with two equal 20 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  32. 32.📏 Which unit measures the flow of charge? (a) ampere (A) (b) ohm (Ω) (c) volt (V) (d) watt (W)
  33. 33.🧩 Which component lets current go one way? (a) diode (b) resistor (c) capacitor (d) potentiometer
  34. 34.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = R ÷ I (c) V = I × R (d) V = I + R
  35. 35.🌈 A resistor has the colour bands orange, black, orange. What is its value in kilo-ohms (kΩ)? =
  36. 36.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 5 % (c) 50 % (d) 0 %
  37. 37.🔺 A current of 10 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  38. 38.🔺 A 1.25 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  39. 39.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets smaller (c) becomes zero (d) gets bigger
  40. 40.🌈 A resistor has the colour bands violet, white, orange. What is its value (in ohms)?

Answer key

  1. True
  2. I = V ÷ R
  3. 20
  4. an LED lamp
  5. P = V × I
  6. to limit the current
  7. 0.1
  8. 10
  9. 43
  10. 0.3
  11. True
  12. 1.5
  13. 0.2
  14. 1 kilowatt-hour (kWh)
  15. False
  16. current
  17. 4
  18. 5
  19. 1.5
  20. 8800
  21. saves electricity
  22. does not light
  23. 30
  24. resistor
  25. 6
  26. 2
  27. 502
  28. store charge briefly
  29. 9.6
  30. 1
  31. 57
  32. ampere (A)
  33. diode
  34. V = I × R
  35. 30
  36. 5 %
  37. 3
  38. 0.25
  39. gets smaller
  40. 79000

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