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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 183 · 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: voltage is measured in volts (V). (a) True (b) False
  2. 2.🧮 Resistors of 20 Ω, 47 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
  3. 3.🌈 A resistor has the colour bands violet, black, orange. What is its value in kilo-ohms (kΩ)? =
  4. 4.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
  5. 5.Which of these is measured in volts (V)? (a) the push of a cell (b) the flow of charge (c) how much a part resists (d) current
  6. 6.🧾 Which lamp gives the same light for the least power? (a) an oil lamp (b) a candle (c) a filament bulb (d) an LED lamp
  7. 7.Which of these wastes electricity? (a) set the AC to 24 °C (b) leave the TV on standby (c) switch off empty rooms (d) unplug idle chargers
  8. 8.🔺 A current of 50 mA flows when 12.5 V is joined across a resistor. What is its resistance (in ohms)?
  9. 9.🧮 Three equal 30 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  10. 10.🔺 A current of 2.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  11. 11.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
  12. 12.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 23000 Ω resistor? (a) red-orange-red (b) orange-red-orange (c) red-orange-orange (d) red-orange-yellow
  13. 13.💡 Does it save or waste electricity to switch off empty rooms? (a) saves electricity (b) wastes electricity
  14. 14.💡 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) may burn out (c) does not light
  15. 15.🔺 A current of 2.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  16. 16.⚡ A device works on 9 V and takes 1.5 A. What is its power (in watts)? =
  17. 17.⚡ A 0.15 W device works on 1.5 V. What current does it take (in amperes)? =
  18. 18.🧮 Resistors of 22 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
  19. 19.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  20. 20.🔺 A current of 0.2 A flows when 0.4 V is joined across a resistor. What is its resistance (in ohms)?
  21. 21.🌈 In the resistor colour code, which number does grey stand for?
  22. 22.🔺 A 3.75 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  23. 23.🌈 A resistor has the colour bands orange, orange, orange. What is its value in kilo-ohms (kΩ)? =
  24. 24.🔺 A current of 2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.📏 How many milliamperes (mA) make 1 ampere? (a) 100 (b) 60 (c) 1000 (d) 10
  26. 26.🔺 A current of 10 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  27. 27.🌈 A resistor has the colour bands blue, red, yellow. What is its value in kilo-ohms (kΩ)? =
  28. 28.🔺 A current of 50 mA flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  29. 29.🧮 A 15 V battery is joined to 10 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
  30. 30.🔺 A 12.5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
  31. 31.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
  32. 32.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = I ÷ V (c) R = V ÷ I (d) R = V + I
  33. 33.What does an LED do? (a) glows using little power (b) is a resistance knob (c) smooths a wobbly supply (d) boosts a small signal
  34. 34.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.🔺 A 7.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  36. 36.🌈 In the resistor colour code, which number does red stand for?
  37. 37.🧾 A family uses 30 units of electricity in a month and each unit costs ₹6. What is the bill (in ₹)?
  38. 38.What does a fuse do? (a) makes things spin (b) blows if current is high (c) boosts a small signal (d) glows using little power
  39. 39.🔺 A 3 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  40. 40.📏 In the water-pipe picture of a circuit, resistance is like … (a) a bigger tank (b) the flow of water (c) the water pressure (d) a narrow pipe

Answer key

  1. True
  2. 87
  3. 70
  4. True
  5. the push of a cell
  6. an LED lamp
  7. leave the TV on standby
  8. 250
  9. 10
  10. 25
  11. True
  12. red-orange-orange
  13. saves electricity
  14. does not light
  15. 12.5
  16. 13.5
  17. 0.1
  18. 32
  19. 165
  20. 2
  21. 8
  22. 25
  23. 33
  24. 20
  25. 1000
  26. 5
  27. 620
  28. 120
  29. 1
  30. 50
  31. True
  32. R = V ÷ I
  33. glows using little power
  34. 2.2
  35. 50
  36. 2
  37. 180
  38. blows if current is high
  39. 20
  40. a narrow pipe

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