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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 808 · 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 red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3.5 V supply. What current flows (in mA)?
  2. 2.🔺 A current of 1 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  3. 3.🔺 A current of 25 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  4. 4.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) bigger (c) stay the same (d) zero
  5. 5.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 4 V supply. What current flows (in mA)?
  6. 6.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) gets bigger (c) becomes zero (d) stays the same
  7. 7.🧮 A 2.6 V battery is joined to 3 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
  8. 8.🔺 A current of 3 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  9. 9.🧮 Five equal 500 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  10. 10.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
  11. 11.🔺 A current of 40 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  12. 12.True or false: resistance is measured in ohms (Ω). (a) False (b) True
  13. 13.🧩 Which component senses how bright it is? (a) diode (b) LDR (c) resistor (d) potentiometer
  14. 14.True or false: a resistor limits the current. (a) False (b) True
  15. 15.🔺 A current of 40 mA flows when 13.2 V is joined across a resistor. What is its resistance (in ohms)?
  16. 16.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 30000 Ω resistor? (a) yellow-orange-orange (b) orange-black-orange (c) orange-black-yellow (d) orange-black-red
  17. 17.🔺 A 5 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
  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.🔺 A 60 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  20. 20.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
  21. 21.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it changes colour (c) it does not light (d) it makes a sound
  22. 22.🔺 A current of 3 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to an 8 V supply. What current flows (in mA)?
  24. 24.True or false: to switch off empty rooms wastes electricity. (a) True (b) False
  25. 25.🔺 A 4 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  26. 26.📏 In the water-pipe picture of a circuit, voltage is like … (a) the water tank lid (b) the pipe colour (c) the tap handle (d) the water pressure
  27. 27.🧩 Which part changes electrical energy into movement? (a) a resistor (b) a motor (c) an LED (d) a fuse
  28. 28.True or false: a thermistor is a resistance knob. (a) True (b) False
  29. 29.🧮 A 33 Ω resistor is joined in series with two equal 1000 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  30. 30.What does a resistor do? (a) boosts a small signal (b) has coloured bands (c) senses how hot it is (d) glows using little power
  31. 31.🧾 A family uses 40 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
  32. 32.True or false: the ammeter is joined across a part. (a) True (b) False
  33. 33.Which of these is measured in watts (W)? (a) current (b) how much a part resists (c) voltage (d) power
  34. 34.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  35. 35.True or false: a transistor boosts a small signal. (a) False (b) True
  36. 36.What does a buzzer do? (a) lets current go one way (b) boosts a small signal (c) limits the current (d) beeps for an alarm
  37. 37.🌈 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
  38. 38.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  39. 39.🧮 A 3 V battery is joined to 2 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
  40. 40.What does a motor do? (a) limits the current (b) stores a little charge (c) makes things spin (d) has coloured bands

Answer key

  1. 15
  2. 10
  3. 200
  4. bigger
  5. 20
  6. gets smaller
  7. 0.2
  8. 9
  9. 100
  10. voltmeter
  11. 6
  12. True
  13. LDR
  14. True
  15. 330
  16. orange-black-orange
  17. 25
  18. P = V × I
  19. 3
  20. ammeter
  21. it does not light
  22. 30
  23. 20
  24. False
  25. 0.2
  26. the water pressure
  27. a motor
  28. False
  29. 533
  30. has coloured bands
  31. 280
  32. False
  33. power
  34. anode (+)
  35. True
  36. beeps for an alarm
  37. the one nearest an end
  38. 10
  39. 0.5
  40. makes things spin

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