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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 525 · 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) leave fridge door open (c) close the fridge quickly (d) unplug idle chargers
  2. 2.True or false: a resistor has coloured bands. (a) True (b) False
  3. 3.Which of these wastes electricity? (a) use old filament bulbs (b) switch off empty rooms (c) close the fridge quickly (d) use daylight to read
  4. 4.🧮 An 8 V battery is joined to 10 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
  5. 5.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 3.5 V supply. What current flows (in mA)?
  6. 6.🧩 Which part changes electrical energy into movement? (a) a resistor (b) a fuse (c) a motor (d) an LED
  7. 7.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  8. 8.📏 How many amperes (A) is 2730 mA? =
  9. 9.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  10. 10.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = V + I (c) R = I ÷ V (d) R = V ÷ I
  11. 11.📏 How many milliamperes (mA) is 2.25 A?
  12. 12.Which of these is measured in watts (W)? (a) resistance (b) voltage (c) current (d) power
  13. 13.True or false: a thermistor has coloured bands. (a) True (b) False
  14. 14.🔺 A current of 25 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.🔺 A 10 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
  16. 16.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it does not light (c) it makes a sound (d) it lights brighter
  17. 17.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I + R (c) V = I × R (d) V = R ÷ I
  18. 18.🔺 A current of 0.25 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  19. 19.True or false: energy used each second is measured in watts (W). (a) True (b) False
  20. 20.⚡ A device works on 24 V and takes 0.25 A. What is its power (in watts)? =
  21. 21.⚡ A 0.6 W device works on 6 V. What current does it take (in amperes)? =
  22. 22.🌈 A resistor has the colour bands violet, green, black. What is its value (in ohms)?
  23. 23.🧮 A 33 Ω resistor is joined in series with two equal 50 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  24. 24.True or false: the voltmeter is joined in series. (a) False (b) True
  25. 25.🧾 A family uses 180 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
  26. 26.🧮 Resistors of 150 Ω, 220 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
  27. 27.🔍 Which is the odd one out? (a) leave the TV on standby (b) run fans in empty rooms (c) switch off empty rooms (d) iron one shirt at a time
  28. 28.🔺 A 2.5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
  29. 29.⚡ Power tells us … (a) energy used each second (b) the size of a cell (c) the length of a wire (d) the colour of light
  30. 30.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 3600 Ω resistor? (a) orange-blue-red (b) orange-blue-orange (c) blue-orange-red (d) orange-blue-brown
  31. 31.🔺 A current of 1.5 A flows when 30 V is joined across a resistor. What is its resistance (in ohms)?
  32. 32.📏 Which unit measures the push of a cell? (a) watt (W) (b) ohm (Ω) (c) ampere (A) (d) volt (V)
  33. 33.🔺 A current of 10 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  34. 34.🔺 A 1.25 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  35. 35.⚡ Which formula gives electric power? (a) P = V × I (b) P = V ÷ I (c) P = I ÷ V (d) P = V + I
  36. 36.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = R ÷ V (c) I = V × R (d) I = V ÷ R
  37. 37.⚡ A device works on 9 V and takes 2 A. What is its power (in watts)? =
  38. 38.🌈 Which band is read first on a resistor? (a) the widest gap (b) any band (c) the one nearest an end (d) the gold band
  39. 39.💡 An LED is joined to a 3 V battery through a 1000 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) lights up (b) may burn out (c) does not light
  40. 40.🧮 Four equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?

Answer key

  1. leave fridge door open
  2. True
  3. use old filament bulbs
  4. 0.5
  5. 10
  6. a motor
  7. 100
  8. 2.73
  9. 500
  10. R = V ÷ I
  11. 2250
  12. power
  13. False
  14. 5
  15. 40
  16. it does not light
  17. V = I × R
  18. 1.5
  19. True
  20. 6
  21. 0.1
  22. 75
  23. 58
  24. False
  25. 1260
  26. 520
  27. switch off empty rooms
  28. 10
  29. energy used each second
  30. orange-blue-red
  31. 20
  32. volt (V)
  33. 1.5
  34. 0.25
  35. P = V × I
  36. I = V ÷ R
  37. 18
  38. the one nearest an end
  39. does not light
  40. 25

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