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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 6 · 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.Which of these wastes electricity? (a) set the AC to 24 °C (b) switch off empty rooms (c) use daylight to read (d) iron one shirt at a time
  2. 2.🧾 Which lamp gives the same light for the least power? (a) an LED lamp (b) a candle (c) a filament bulb (d) an oil lamp
  3. 3.🔺 A 15 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  4. 4.🔺 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
  5. 5.🔺 A current of 1.5 A flows when 15 V is joined across a resistor. What is its resistance (in ohms)?
  6. 6.🌈 A resistor has the colour bands green, black, orange. What is its value (in ohms)?
  7. 7.Which of these wastes electricity? (a) set the AC to 24 °C (b) leave the TV on standby (c) unplug idle chargers (d) use daylight to read
  8. 8.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) stays the same (c) gets smaller (d) becomes zero
  9. 9.🔺 A current of 10 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  10. 10.Which of these saves electricity? (a) iron one shirt at a time (b) set the AC to 24 °C (c) use old filament bulbs (d) leave the TV on standby
  11. 11.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 4 V supply. What current flows (in mA)?
  12. 12.📏 Which unit measures power? (a) volt (V) (b) watt (W) (c) ampere (A) (d) ohm (Ω)
  13. 13.📏 How many milliamperes (mA) make 1 ampere? (a) 60 (b) 100 (c) 1000 (d) 10
  14. 14.🌈 A resistor has the colour bands yellow, yellow, black. What is its value (in ohms)?
  15. 15.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 6 hours. How many watt-hours (Wh) are saved?
  16. 16.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = I ÷ R (c) V = R ÷ I (d) V = I × R
  17. 17.🌈 A resistor has the colour bands grey, brown, orange. What is its value (in ohms)?
  18. 18.🧩 A capacitor in a circuit can … (a) measure heat (b) store charge briefly (c) spin a wheel (d) make light
  19. 19.🔺 A 1.2 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  20. 20.True or false: to close the fridge quickly saves electricity. (a) False (b) True
  21. 21.🌈 A resistor has the colour bands white, white, orange. What is its value in kilo-ohms (kΩ)? =
  22. 22.🔺 A current of 10 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 79000 Ω resistor? (a) violet-white-red (b) violet-white-yellow (c) white-violet-orange (d) violet-white-orange
  24. 24.🔺 A 0.6 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  25. 25.⚡ Power tells us … (a) the size of a cell (b) energy used each second (c) the length of a wire (d) the colour of light
  26. 26.🧾 A family uses 20 units of electricity in a month and each unit costs ₹9. What is the bill (in ₹)?
  27. 27.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) False (b) True
  28. 28.⚡ Which formula gives electric power? (a) P = V + I (b) P = V × I (c) P = I ÷ V (d) P = V ÷ I
  29. 29.⚡ A device works on 6 V and takes 0.2 A. What is its power (in watts)? =
  30. 30.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) stay the same (c) zero (d) bigger
  31. 31.⚡ A device works on 3 V and takes 0.1 A. What is its power (in watts)? =
  32. 32.True or false: an LDR senses how bright it is. (a) False (b) True
  33. 33.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
  34. 34.🌈 A resistor has the colour bands green, grey, red. What is its value (in ohms)?
  35. 35.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 5 hours. How many watt-hours (Wh) are saved?
  36. 36.⚡ A device works on 3 V and takes 0.25 A. What is its power (in watts)? =
  37. 37.🔺 A current of 25 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  38. 38.💡 An LED is joined to a 9 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) does not light (c) lights up
  39. 39.🧾 A 50 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
  40. 40.True or false: the push of a cell is measured in volts (V). (a) True (b) False

Answer key

  1. iron one shirt at a time
  2. an LED lamp
  3. 3
  4. I = V ÷ R
  5. 10
  6. 50000
  7. leave the TV on standby
  8. gets smaller
  9. 5
  10. set the AC to 24 °C
  11. 10
  12. watt (W)
  13. 1000
  14. 44
  15. 306
  16. V = I × R
  17. 81000
  18. store charge briefly
  19. 10
  20. True
  21. 99
  22. 4.7
  23. violet-white-orange
  24. 0.1
  25. energy used each second
  26. 180
  27. True
  28. P = V × I
  29. 1.2
  30. bigger
  31. 0.3
  32. True
  33. ammeter
  34. 5800
  35. 255
  36. 0.75
  37. 10
  38. may burn out
  39. 0.4
  40. True

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