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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 395 · 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 band is read first on a resistor? (a) the gold band (b) any band (c) the widest gap (d) the one nearest an end
  2. 2.🔺 A current of 25 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  3. 3.🔺 A current of 50 mA flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
  4. 4.🔍 Which is the odd one out? (a) switch off empty rooms (b) use old filament bulbs (c) leave the TV on standby (d) iron one shirt at a time
  5. 5.🧮 Resistors of 150 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
  6. 6.🔺 A current of 0.5 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  7. 7.🧾 Which lamp gives the same light for the least power? (a) an oil lamp (b) an LED lamp (c) a filament bulb (d) a candle
  8. 8.🧩 Which component senses how hot it is? (a) diode (b) capacitor (c) thermistor (d) LDR
  9. 9.🔺 A current of 2.5 A flows when 15 V is joined across a resistor. What is its resistance (in ohms)?
  10. 10.⚡ A device works on 1.5 V and takes 3 A. What is its power (in watts)? =
  11. 11.📏 Which unit measures how much a part resists? (a) watt (W) (b) ohm (Ω) (c) volt (V) (d) ampere (A)
  12. 12.🔺 A current of 1.5 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  13. 13.⚡ A device works on 12 V and takes 0.2 A. What is its power (in watts)? =
  14. 14.🌈 A resistor has the colour bands green, grey, red. What is its value (in ohms)?
  15. 15.🔺 A current of 0.1 A flows when 0.5 V is joined across a resistor. What is its resistance (in ohms)?
  16. 16.📏 Which unit measures voltage? (a) ampere (A) (b) ohm (Ω) (c) volt (V) (d) watt (W)
  17. 17.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 kilowatt-hour (kWh) (c) 1 watt (d) 1 ampere
  18. 18.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V × I (c) P = V + I (d) P = V ÷ I
  19. 19.True or false: the push of a cell is measured in volts (V). (a) False (b) True
  20. 20.🧮 Four equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  21. 21.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  22. 22.🔺 A current of 40 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.🔺 A current of 0.2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  24. 24.💡 Does it save or waste electricity to unplug idle chargers? (a) saves electricity (b) wastes electricity
  25. 25.🔺 A current of 2.5 A flows when 25 V is joined across a resistor. What is its resistance (in ohms)?
  26. 26.🔺 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
  27. 27.🧮 A 10 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)?
  28. 28.🔺 A 24 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  29. 29.💡 Does it save or waste electricity to set the AC to 24 °C? (a) saves electricity (b) wastes electricity
  30. 30.🔺 A current of 50 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.🧩 A capacitor in a circuit can … (a) make light (b) store charge briefly (c) spin a wheel (d) measure heat
  32. 32.🧮 Three equal 150 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  33. 33.True or false: a buzzer beeps for an alarm. (a) False (b) True
  34. 34.🔺 A current of 0.2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  36. 36.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 50 Ω resistor? (a) green-black-brown (b) blue-black-black (c) green-black-black (d) blue-green-black
  37. 37.⚡ A 0.3 W device works on 1.5 V. What current does it take (in amperes)? =
  38. 38.🔺 A 30 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  39. 39.What does a diode do? (a) has coloured bands (b) lets current go one way (c) stores a little charge (d) is a resistance knob
  40. 40.📏 How many milliamperes (mA) is 2.73 A?

Answer key

  1. the one nearest an end
  2. 6.25
  3. 400
  4. switch off empty rooms
  5. 620
  6. 4
  7. an LED lamp
  8. thermistor
  9. 6
  10. 4.5
  11. ohm (Ω)
  12. 4
  13. 2.4
  14. 5800
  15. 5
  16. volt (V)
  17. 1 kilowatt-hour (kWh)
  18. P = V × I
  19. True
  20. 25
  21. anode (+)
  22. 8
  23. 0.6
  24. saves electricity
  25. 10
  26. R = V ÷ I
  27. 30
  28. 3
  29. saves electricity
  30. 5
  31. store charge briefly
  32. 50
  33. True
  34. 0.8
  35. cathode (−)
  36. green-black-black
  37. 0.2
  38. 3
  39. lets current go one way
  40. 2730

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