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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 110 · 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.🔺 A current of 2.5 A flows when 37.5 V is joined across a resistor. What is its resistance (in ohms)?
  2. 2.🔺 A current of 1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  3. 3.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V × I (d) P = V ÷ I
  4. 4.True or false: on an LED, the shorter leg is the cathode (−). (a) True (b) False
  5. 5.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 590 Ω resistor? (a) green-white-red (b) green-white-brown (c) green-white-black (d) white-green-brown
  6. 6.True or false: on an LED, the round-side leg is the anode (+). (a) True (b) False
  7. 7.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
  8. 8.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 56000 Ω resistor? (a) green-blue-orange (b) green-blue-yellow (c) blue-green-orange (d) green-blue-red
  9. 9.🧩 Which component turns a fan or wheels? (a) motor (b) resistor (c) potentiometer (d) LED
  10. 10.🧮 A 20 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.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 480 Ω resistor? (a) yellow-grey-black (b) yellow-grey-brown (c) grey-yellow-brown (d) yellow-grey-red
  12. 12.🔺 A 16 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  13. 13.🔺 A current of 0.5 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.🔺 In the V-I-R triangle, how do we find I? (a) I = V ÷ R (b) I = R ÷ V (c) I = V × R (d) I = V + R
  15. 15.🔺 A 0.3 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  16. 16.🔺 A current of 0.25 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.🧾 One “unit” on an electricity bill is … (a) 1 kilowatt-hour (kWh) (b) 1 volt (c) 1 ampere (d) 1 watt
  18. 18.🧩 Which component beeps for an alarm? (a) potentiometer (b) buzzer (c) thermistor (d) fuse
  19. 19.What does a capacitor do? (a) limits the current (b) blows if current is high (c) stores a little charge (d) makes a beeping sound
  20. 20.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) the widest gap (c) any band (d) the gold band
  21. 21.Which of these saves electricity? (a) leave the TV on standby (b) use old filament bulbs (c) iron one shirt at a time (d) unplug idle chargers
  22. 22.🧩 Which component glows using little power? (a) LED (b) resistor (c) buzzer (d) fuse
  23. 23.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 50 % (c) 25 % (d) 5 %
  24. 24.True or false: on an LED, the shorter leg is the anode (+). (a) True (b) False
  25. 25.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  26. 26.🧮 A 4 V battery is joined to 10 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
  27. 27.📏 In the water-pipe picture of a circuit, current is like … (a) the pipe colour (b) the water pressure (c) a narrow pipe (d) the flow of water
  28. 28.True or false: power is measured in watts (W). (a) False (b) True
  29. 29.🔺 A 2.5 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  30. 30.🧮 A 0.6 V battery is joined to 2 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
  31. 31.🔺 A current of 20 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  32. 32.🔺 A current of 0.2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  33. 33.🔺 A current of 1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  34. 34.📏 Which unit measures power? (a) ampere (A) (b) ohm (Ω) (c) volt (V) (d) watt (W)
  35. 35.🧾 A 1500 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
  36. 36.🔺 A current of 0.2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  37. 37.💡 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) lights up (c) does not light
  38. 38.🌈 In the resistor colour code, which number does black stand for?
  39. 39.🧮 Resistors of 47 Ω, 330 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
  40. 40.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) stay the same (c) smaller (d) zero

Answer key

  1. 15
  2. 20
  3. P = V × I
  4. True
  5. green-white-brown
  6. True
  7. ammeter
  8. green-blue-orange
  9. motor
  10. 120
  11. yellow-grey-brown
  12. 40
  13. 7.5
  14. I = V ÷ R
  15. 0.1
  16. 0.75
  17. 1 kilowatt-hour (kWh)
  18. buzzer
  19. stores a little charge
  20. the one nearest an end
  21. unplug idle chargers
  22. LED
  23. 5 %
  24. False
  25. anode (+)
  26. 0.2
  27. the flow of water
  28. True
  29. 0.25
  30. 0.1
  31. 3
  32. 0.8
  33. 3
  34. watt (W)
  35. 3
  36. 0.6
  37. does not light
  38. 0
  39. 527
  40. bigger

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