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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 155 · 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.

NameDateTime takenScore ___ / 40
  1. 1.⚡ A device works on 6 V and takes 0.2 A. What is its power (in watts)? =
  2. 2.🔍 Which is the odd one out? (a) close the fridge quickly (b) set the AC to 24 °C (c) switch off empty rooms (d) leave fridge door open
  3. 3.🔺 A current of 0.2 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  4. 4.🌈 A resistor has the colour bands brown, grey, brown. What is its value (in ohms)?
  5. 5.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets bigger (c) stays the same (d) gets smaller
  6. 6.True or false: the ammeter measures current. (a) False (b) True
  7. 7.🧮 Four equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  8. 8.🌈 In the resistor colour code, which number does red stand for?
  9. 9.🔺 A current of 50 mA flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
  10. 10.📏 How many watts (W) is 3.4 kW?
  11. 11.🧩 A capacitor in a circuit can … (a) spin a wheel (b) store charge briefly (c) make light (d) measure heat
  12. 12.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V ÷ R (c) I = V + R (d) I = R ÷ V
  13. 13.What does a resistor do? (a) senses how hot it is (b) lets current go one way (c) has coloured bands (d) is a resistance knob
  14. 14.🌈 A resistor has the colour bands green, green, yellow. What is its value in kilo-ohms (kΩ)? =
  15. 15.🧾 A 200 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
  16. 16.🧩 Which component boosts a small signal? (a) LDR (b) capacitor (c) transistor (d) diode
  17. 17.🔺 A 3.3 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
  18. 18.⚡ A 2.4 W device works on 12 V. What current does it take (in amperes)? =
  19. 19.True or false: a transistor boosts a small signal. (a) True (b) False
  20. 20.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1024 (b) 10 (c) 100 (d) 1000
  21. 21.🔺 A 30 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  22. 22.🔺 A 7.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  23. 23.🔺 A 0.75 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  24. 24.🧾 A family uses 110 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
  25. 25.💡 Does it save or waste electricity to close the fridge quickly? (a) saves electricity (b) wastes electricity
  26. 26.🔺 A 1 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  27. 27.True or false: a diode lets current go one way. (a) False (b) True
  28. 28.📏 How many watts (W) is 0.8 kW?
  29. 29.📏 How many watts (W) is 1.6 kW?
  30. 30.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
  31. 31.🔺 A 1.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  32. 32.🧮 A 2 V battery is joined to 6 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
  33. 33.True or false: a fuse boosts a small signal. (a) False (b) True
  34. 34.📏 How many kilowatts (kW) is 1000 W? =
  35. 35.🔺 A current of 25 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.📏 In the water-pipe picture of a circuit, current is like … (a) the pipe colour (b) the flow of water (c) the water pressure (d) a narrow pipe
  37. 37.🌈 A resistor has the colour bands violet, violet, red. What is its value (in ohms)?
  38. 38.True or false: an LDR is a resistance knob. (a) True (b) False
  39. 39.📏 How many milliamperes (mA) make 1 ampere? (a) 10 (b) 60 (c) 1000 (d) 100
  40. 40.💡 An LED is joined to a 9 V battery through a 470 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) lights up (b) does not light (c) may burn out

Answer key

  1. 1.2
  2. leave fridge door open
  3. 2.4
  4. 180
  5. gets smaller
  6. True
  7. 50
  8. 2
  9. 150
  10. 3400
  11. store charge briefly
  12. I = V ÷ R
  13. has coloured bands
  14. 550
  15. 2
  16. transistor
  17. 10
  18. 0.2
  19. True
  20. 1000
  21. 2.5
  22. 50
  23. 0.25
  24. 440
  25. saves electricity
  26. 10
  27. True
  28. 800
  29. 1600
  30. ammeter
  31. 10
  32. 0.25
  33. False
  34. 1
  35. 2.5
  36. the flow of water
  37. 7700
  38. False
  39. 1000
  40. does not light

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