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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 688 · 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 amperes (A) is 1220 mA? =
  2. 2.🌈 A resistor has the colour bands grey, red, red. What is its value (in ohms)?
  3. 3.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V ÷ I (c) P = V × I (d) P = V + I
  4. 4.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  5. 5.True or false: a potentiometer turns a fan or wheels. (a) True (b) False
  6. 6.🧮 Four equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  7. 7.📏 How many watts (W) is 4.6 kW?
  8. 8.🧩 Which component senses how hot it is? (a) transistor (b) buzzer (c) thermistor (d) resistor
  9. 9.💡 What does LED stand for? (a) light-emitting diode (b) large electric dial (c) light energy dial (d) low energy device
  10. 10.🧮 A 100 Ω resistor is joined in series with two equal 200 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  11. 11.🧮 Resistors of 330 Ω, 47 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
  12. 12.🌈 Which band is read first on a resistor? (a) the widest gap (b) the gold band (c) the one nearest an end (d) any band
  13. 13.🧮 A 470 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)?
  14. 14.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to make it brighter (c) to store charge (d) to change its colour
  15. 15.🔺 A current of 1 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  16. 16.💡 An LED is joined to a 6 V battery through a 220 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) lights up (b) may burn out (c) does not light
  17. 17.🔺 An 11 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
  18. 18.Which of these saves electricity? (a) unplug idle chargers (b) iron one shirt at a time (c) leave the TV on standby (d) use old filament bulbs
  19. 19.Which of these is measured in ohms (Ω)? (a) resistance (b) current (c) the push of a cell (d) power
  20. 20.🔺 A current of 1 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  21. 21.True or false: on an LED, the shorter leg is the anode (+). (a) True (b) False
  22. 22.🌈 In the resistor colour code, which number does brown stand for?
  23. 23.🧩 Which component limits the current? (a) capacitor (b) resistor (c) potentiometer (d) LDR
  24. 24.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets bigger (c) stays the same (d) gets smaller
  25. 25.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  26. 26.🔺 A current of 40 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  27. 27.⚡ A 2.4 W device works on 12 V. What current does it take (in amperes)? =
  28. 28.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) stay the same (c) smaller (d) bigger
  29. 29.🔺 A current of 1.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.🔺 A current of 1.5 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.🔺 A current of 1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  32. 32.⚡ A 72 W device works on 24 V. What current does it take (in amperes)? =
  33. 33.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I + R (c) V = I × R (d) V = I ÷ R
  34. 34.🧩 Which component smooths a wobbly supply? (a) potentiometer (b) capacitor (c) motor (d) LED
  35. 35.What does a capacitor do? (a) has coloured bands (b) lets current go one way (c) boosts a small signal (d) stores a little charge
  36. 36.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
  37. 37.🔺 In the V-I-R triangle, how do we find R? (a) R = V + I (b) R = V ÷ I (c) R = V × I (d) R = I ÷ V
  38. 38.🧾 A 100 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
  39. 39.💡 Does it save or waste electricity to use daylight to read? (a) wastes electricity (b) saves electricity
  40. 40.🧾 A 500 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =

Answer key

  1. 1.22
  2. 8200
  3. P = V × I
  4. 25
  5. False
  6. 50
  7. 4600
  8. thermistor
  9. light-emitting diode
  10. 200
  11. 410
  12. the one nearest an end
  13. 475
  14. to limit the current
  15. 8
  16. does not light
  17. 50
  18. unplug idle chargers
  19. resistance
  20. 5
  21. False
  22. 1
  23. resistor
  24. gets smaller
  25. 5
  26. 4
  27. 0.2
  28. bigger
  29. 30
  30. 3
  31. 3
  32. 3
  33. V = I × R
  34. capacitor
  35. stores a little charge
  36. ammeter
  37. R = V ÷ I
  38. 0.2
  39. saves electricity
  40. 4

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