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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 966 · 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.What does a motor do? (a) makes things spin (b) is a resistance knob (c) limits the current (d) boosts a small signal
  2. 2.⚡ Power tells us … (a) energy used each second (b) the colour of light (c) the length of a wire (d) the size of a cell
  3. 3.Which of these wastes electricity? (a) use LED lamps (b) set the AC to 24 °C (c) leave the TV on standby (d) use daylight to read
  4. 4.What does a resistor do? (a) limits the current (b) lets current go one way (c) beeps for an alarm (d) senses how bright it is
  5. 5.💡 Does it save or waste electricity to iron one shirt at a time? (a) saves electricity (b) wastes electricity
  6. 6.⚡ A 0.5 W device works on 5 V. What current does it take (in amperes)? =
  7. 7.💡 An LED is joined to a 12 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) lights up (c) may burn out
  8. 8.🧩 A capacitor in a circuit can … (a) store charge briefly (b) measure heat (c) make light (d) spin a wheel
  9. 9.🧮 A 100 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)?
  10. 10.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  11. 11.What does a thermistor do? (a) makes things spin (b) glows using little power (c) is a resistance knob (d) senses how hot it is
  12. 12.🧮 A 22 Ω resistor is joined in series with two equal 470 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  13. 13.🧮 Resistors of 10 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
  14. 14.True or false: how much a part resists is measured in ohms (Ω). (a) False (b) True
  15. 15.True or false: the voltmeter measures voltage. (a) True (b) False
  16. 16.🔺 A current of 10 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V ÷ R (c) I = V × R (d) I = V + R
  18. 18.True or false: on an LED, the round-side leg is the anode (+). (a) True (b) False
  19. 19.🧮 A 33 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)?
  20. 20.💡 Does it save or waste electricity to leave fridge door open? (a) wastes electricity (b) saves electricity
  21. 21.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) smaller (c) zero (d) bigger
  22. 22.True or false: to leave fridge door open saves electricity. (a) True (b) False
  23. 23.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) any band (c) the gold band (d) the widest gap
  24. 24.🔍 Which is the odd one out? (a) leave the TV on standby (b) iron one shirt at a time (c) set the AC to 24 °C (d) run fans in empty rooms
  25. 25.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V + I (c) P = V × I (d) P = V ÷ I
  26. 26.🔺 A current of 10 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  27. 27.⚡ A device works on 9 V and takes 2 A. What is its power (in watts)? =
  28. 28.🔺 A 1 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  29. 29.🧾 A family uses 40 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
  30. 30.🔺 A current of 0.1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.📏 In the water-pipe picture of a circuit, resistance is like … (a) the flow of water (b) a narrow pipe (c) the water pressure (d) a bigger tank
  32. 32.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 25 % (c) 0 % (d) 50 %
  33. 33.🔺 A current of 50 mA flows when 25 V is joined across a resistor. What is its resistance (in ohms)?
  34. 34.🔺 A 16.5 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
  35. 35.🌈 A resistor has the colour bands violet, violet, red. What is its value in kilo-ohms (kΩ)? =
  36. 36.💡 A red LED uses 2 V and should get 10 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
  37. 37.🔍 Which is the odd one out? (a) set the AC to 24 °C (b) leave the TV on standby (c) close the fridge quickly (d) use LED lamps
  38. 38.⚡ A 0.3 W device works on 3 V. What current does it take (in amperes)? =
  39. 39.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) their sum (c) more than either one (d) always zero
  40. 40.🔺 A current of 0.2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =

Answer key

  1. makes things spin
  2. energy used each second
  3. leave the TV on standby
  4. limits the current
  5. wastes electricity
  6. 0.1
  7. may burn out
  8. store charge briefly
  9. 120
  10. 100
  11. senses how hot it is
  12. 257
  13. 78
  14. True
  15. True
  16. 2
  17. I = V ÷ R
  18. True
  19. 43
  20. wastes electricity
  21. bigger
  22. False
  23. the one nearest an end
  24. set the AC to 24 °C
  25. P = V × I
  26. 3.3
  27. 18
  28. 0.25
  29. 280
  30. 0.3
  31. a narrow pipe
  32. 5 %
  33. 500
  34. 50
  35. 7.7
  36. 400
  37. leave the TV on standby
  38. 0.1
  39. less than either one
  40. 0.8

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