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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 227 · 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 is the odd one out? (a) use daylight to read (b) leave fridge door open (c) use old filament bulbs (d) leave the TV on standby
  2. 2.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  3. 3.🔺 A current of 1 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  4. 4.🌈 A resistor has the colour bands green, black, red. What is its value (in ohms)?
  5. 5.💡 Does it save or waste electricity to iron one shirt at a time? (a) wastes electricity (b) saves electricity
  6. 6.🧩 Which part changes electrical energy into movement? (a) a resistor (b) an LED (c) a motor (d) a fuse
  7. 7.💡 An LED is joined to a 3 V battery through a 220 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) lights up (b) does not light (c) may burn out
  8. 8.True or false: energy used each second is measured in watts (W). (a) True (b) False
  9. 9.True or false: power is measured in volts (V). (a) False (b) True
  10. 10.🧩 Which component senses how hot it is? (a) potentiometer (b) fuse (c) thermistor (d) resistor
  11. 11.🧮 A 13 V battery is joined to 3 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
  12. 12.⚡ A 2.25 W device works on 9 V. What current does it take (in amperes)? =
  13. 13.📏 How many milliamperes (mA) is 0.15 A?
  14. 14.🌈 A resistor has the colour bands violet, white, brown. What is its value (in ohms)?
  15. 15.📏 In the water-pipe picture of a circuit, voltage is like … (a) the tap handle (b) the water tank lid (c) the water pressure (d) the pipe colour
  16. 16.⚡ A device works on 3 V and takes 0.1 A. What is its power (in watts)? =
  17. 17.🧾 A family uses 140 units of electricity in a month and each unit costs ₹9. What is the bill (in ₹)?
  18. 18.🔺 A current of 0.1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  19. 19.⚡ A 0.9 W device works on 9 V. What current does it take (in amperes)? =
  20. 20.⚡ Power tells us … (a) the size of a cell (b) the colour of light (c) energy used each second (d) the length of a wire
  21. 21.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 2 hours. How many watt-hours (Wh) are saved?
  22. 22.🧩 A capacitor in a circuit can … (a) make light (b) spin a wheel (c) store charge briefly (d) measure heat
  23. 23.🔺 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
  24. 24.🔺 A current of 25 mA flows when 6.25 V is joined across a resistor. What is its resistance (in ohms)?
  25. 25.🌈 In the resistor colour code, which number does blue stand for?
  26. 26.🔺 A current of 20 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  27. 27.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  28. 28.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to limit the current (c) to make it brighter (d) to store charge
  29. 29.🔺 A 5 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  30. 30.🔺 A current of 40 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
  32. 32.True or false: the push of a cell is measured in volts (V). (a) False (b) True
  33. 33.⚡ A 0.375 W device works on 1.5 V. What current does it take (in amperes)? =
  34. 34.⚡ An 18 W device works on 12 V. What current does it take (in amperes)? =
  35. 35.🌈 In the resistor colour code, which number does brown stand for?
  36. 36.True or false: to set the AC to 24 °C wastes electricity. (a) False (b) True
  37. 37.🔺 A current of 10 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  38. 38.🔍 Which is the odd one out? (a) leave the TV on standby (b) switch off empty rooms (c) use old filament bulbs (d) leave fridge door open
  39. 39.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V ÷ I (c) P = V + I (d) P = V × I
  40. 40.🔺 A current of 20 mA flows when 4 V is joined across a resistor. What is its resistance (in ohms)?

Answer key

  1. use daylight to read
  2. 1.2
  3. 5
  4. 5000
  5. wastes electricity
  6. a motor
  7. does not light
  8. True
  9. False
  10. thermistor
  11. 1
  12. 0.25
  13. 150
  14. 790
  15. the water pressure
  16. 0.3
  17. 1260
  18. 0.3
  19. 0.1
  20. energy used each second
  21. 68
  22. store charge briefly
  23. R = V ÷ I
  24. 250
  25. 6
  26. 6.6
  27. cathode (−)
  28. to limit the current
  29. 10
  30. 6
  31. 1150
  32. True
  33. 0.25
  34. 1.5
  35. 1
  36. False
  37. 5
  38. switch off empty rooms
  39. P = V × I
  40. 200

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