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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 101 · 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.🔺 A 1.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  2. 2.🧮 A 3 V battery is joined to 10 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
  3. 3.🧮 A 20 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  4. 4.📏 Which unit measures voltage? (a) ohm (Ω) (b) volt (V) (c) ampere (A) (d) watt (W)
  5. 5.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
  6. 6.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 3 V supply. What current flows (in mA)?
  7. 7.🧩 A capacitor in a circuit can … (a) measure heat (b) make light (c) spin a wheel (d) store charge briefly
  8. 8.🧩 Which component makes a beeping sound? (a) thermistor (b) LDR (c) buzzer (d) motor
  9. 9.💡 Does it save or waste electricity to unplug idle chargers? (a) saves electricity (b) wastes electricity
  10. 10.🔺 A current of 0.1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  11. 11.🌈 In the resistor colour code, which number does grey stand for?
  12. 12.🔺 A current of 25 mA flows when 12.5 V is joined across a resistor. What is its resistance (in ohms)?
  13. 13.🌈 A resistor has the colour bands violet, green, orange. What is its value (in ohms)?
  14. 14.True or false: the ammeter measures voltage. (a) False (b) True
  15. 15.🔺 A current of 0.25 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  16. 16.🔺 A current of 25 mA flows when 6.25 V is joined across a resistor. What is its resistance (in ohms)?
  17. 17.⚡ A 0.9 W device works on 9 V. What current does it take (in amperes)? =
  18. 18.🔺 A current of 3 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  19. 19.True or false: the ammeter is joined across a part. (a) False (b) True
  20. 20.📏 How many milliamperes (mA) is 2.35 A?
  21. 21.🔺 A 45 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  22. 22.🔍 Which is the odd one out? (a) iron one shirt at a time (b) use daylight to read (c) switch off empty rooms (d) unplug idle chargers
  23. 23.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 50 % (c) 5 % (d) 25 %
  24. 24.⚡ Power tells us … (a) the colour of light (b) energy used each second (c) the size of a cell (d) the length of a wire
  25. 25.True or false: the voltmeter measures current. (a) False (b) True
  26. 26.🔺 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
  27. 27.📏 How many amperes (A) is 1730 mA? =
  28. 28.📏 How many watts (W) is 0.4 kW?
  29. 29.What does a thermistor do? (a) blows if current is high (b) stores a little charge (c) turns a fan or wheels (d) senses how hot it is
  30. 30.🔺 A current of 25 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.🧾 A family uses 30 units of electricity in a month and each unit costs ₹8. What is the bill (in ₹)?
  32. 32.⚡ A device works on 5 V and takes 2 A. What is its power (in watts)? =
  33. 33.🧮 Four equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  34. 34.⚡ A 0.75 W device works on 1.5 V. What current does it take (in amperes)? =
  35. 35.🌈 A resistor has the colour bands blue, red, orange. What is its value in kilo-ohms (kΩ)? =
  36. 36.🧮 Two resistors in parallel give a total that is … (a) their sum (b) less than either one (c) always zero (d) more than either one
  37. 37.💡 An LED is joined to a 6 V battery through a 330 Ω 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
  38. 38.🔺 A current of 40 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  39. 39.🔺 A 2.4 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  40. 40.Which of these saves electricity? (a) use LED lamps (b) leave fridge door open (c) iron one shirt at a time (d) use old filament bulbs

Answer key

  1. 10
  2. 0.25
  3. 25
  4. volt (V)
  5. True
  6. 5
  7. store charge briefly
  8. buzzer
  9. saves electricity
  10. 1.2
  11. 8
  12. 500
  13. 75000
  14. False
  15. 1.25
  16. 250
  17. 0.1
  18. 2
  19. False
  20. 2350
  21. 3
  22. iron one shirt at a time
  23. 5 %
  24. energy used each second
  25. False
  26. V = I × R
  27. 1.73
  28. 400
  29. senses how hot it is
  30. 5
  31. 240
  32. 10
  33. 50
  34. 0.5
  35. 62
  36. less than either one
  37. lights up
  38. 18.8
  39. 20
  40. use LED lamps

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