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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 762 · 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: on an LED, the shorter leg is the anode (+). (a) False (b) True
  2. 2.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 kilowatt-hour (kWh) (c) 1 watt (d) 1 ampere
  3. 3.📏 Which unit measures voltage? (a) watt (W) (b) ohm (Ω) (c) ampere (A) (d) volt (V)
  4. 4.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 0 % (d) 5 %
  5. 5.🔺 A 3 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  6. 6.🔺 A 16.5 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
  7. 7.🔺 A 2 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  8. 8.🧮 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)?
  9. 9.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V × I (c) P = V ÷ I (d) P = V + I
  10. 10.🔺 A current of 40 mA flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
  11. 11.🧩 A capacitor in a circuit can … (a) measure heat (b) spin a wheel (c) make light (d) store charge briefly
  12. 12.🧾 A family uses 140 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
  13. 13.🧮 Resistors of 33 Ω, 10 Ω, 33 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
  14. 14.🔺 A current of 20 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.🧮 A 3.75 V battery is joined to 10 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
  16. 16.🔺 A current of 0.25 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.🔺 A current of 0.2 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  18. 18.🔺 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
  19. 19.🔺 A current of 40 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.True or false: an LED stores a little charge. (a) True (b) False
  21. 21.🔺 A current of 40 mA flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
  22. 22.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
  23. 23.🔺 A 12 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
  24. 24.🔺 An 18 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  25. 25.What does a transistor do? (a) senses how hot it is (b) boosts a small signal (c) blows if current is high (d) is a resistance knob
  26. 26.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
  27. 27.🧮 A 22 V battery is joined to 10 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
  28. 28.True or false: on an LED, the shorter leg is the cathode (−). (a) True (b) False
  29. 29.📏 Which unit measures energy used each second? (a) ampere (A) (b) watt (W) (c) volt (V) (d) ohm (Ω)
  30. 30.🧩 Which component senses how hot it is? (a) buzzer (b) transistor (c) LED (d) thermistor
  31. 31.🌈 A resistor has the colour bands red, orange, yellow. What is its value in kilo-ohms (kΩ)? =
  32. 32.📏 Which unit measures power? (a) ohm (Ω) (b) ampere (A) (c) volt (V) (d) watt (W)
  33. 33.🔺 A current of 2.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  34. 34.🔺 A current of 3 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.What does a diode do? (a) makes things spin (b) glows using little power (c) lets current go one way (d) blows if current is high
  36. 36.True or false: to switch off empty rooms saves electricity. (a) True (b) False
  37. 37.📏 In the water-pipe picture of a circuit, current is like … (a) a narrow pipe (b) the pipe colour (c) the flow of water (d) the water pressure
  38. 38.⚡ A device works on 6 V and takes 0.1 A. What is its power (in watts)? =
  39. 39.📏 How many milliamperes (mA) make 1 ampere? (a) 1000 (b) 10 (c) 60 (d) 100
  40. 40.💡 Does it save or waste electricity to unplug idle chargers? (a) saves electricity (b) wastes electricity

Answer key

  1. False
  2. 1 kilowatt-hour (kWh)
  3. volt (V)
  4. 5 %
  5. 20
  6. 50
  7. 0.25
  8. 257
  9. P = V × I
  10. 100
  11. store charge briefly
  12. 980
  13. 144
  14. 3
  15. 0.25
  16. 2.5
  17. 1.2
  18. R = V ÷ I
  19. 4
  20. False
  21. 500
  22. ammeter
  23. 40
  24. 3
  25. boosts a small signal
  26. 920
  27. 1
  28. True
  29. watt (W)
  30. thermistor
  31. 230
  32. watt (W)
  33. 25
  34. 15
  35. lets current go one way
  36. True
  37. the flow of water
  38. 0.6
  39. 1000
  40. saves electricity

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