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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 618 · 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 red LED (it uses 2 V) is joined with a 300 Ω resistor to an 8 V supply. What current flows (in mA)?
  2. 2.🌈 A resistor has the colour bands orange, grey, orange. What is its value in kilo-ohms (kΩ)? =
  3. 3.🔺 A 4.4 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
  4. 4.🌈 A resistor has the colour bands grey, brown, orange. What is its value in kilo-ohms (kΩ)? =
  5. 5.🌈 In the resistor colour code, which number does brown stand for?
  6. 6.🧮 A 20 Ω resistor is joined in series with two equal 220 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  7. 7.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
  8. 8.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  9. 9.⚡ A 48 W device works on 24 V. What current does it take (in amperes)? =
  10. 10.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 25 % (c) 0 % (d) 50 %
  11. 11.🌈 A resistor has the colour bands brown, brown, red. What is its value in kilo-ohms (kΩ)? =
  12. 12.🧩 Which component makes things spin? (a) capacitor (b) buzzer (c) potentiometer (d) motor
  13. 13.🧮 A 220 Ω resistor is joined in series with two equal 470 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  14. 14.🔺 A current of 2.5 A flows when 15 V is joined across a resistor. What is its resistance (in ohms)?
  15. 15.📏 How many milliamperes (mA) is 0.73 A?
  16. 16.📏 In the water-pipe picture of a circuit, current is like … (a) the pipe colour (b) the water pressure (c) the flow of water (d) a narrow pipe
  17. 17.💡 An LED is joined to a 3 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) does not light (c) may burn out
  18. 18.🔺 A current of 2 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  19. 19.🔺 A current of 1 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.🧮 Resistors of 47 Ω, 68 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
  21. 21.🧮 Resistors of 33 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
  22. 22.🔺 A 12.5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
  23. 23.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
  24. 24.🔺 A current of 1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.📏 How many ohms (Ω) is 3.4 kΩ?
  26. 26.🧩 Which component turns a fan or wheels? (a) diode (b) LED (c) fuse (d) motor
  27. 27.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to store charge (c) to make it brighter (d) to change its colour
  28. 28.🌈 In the resistor colour code, which number does green stand for?
  29. 29.🔺 A current of 1.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.🔺 A current of 0.2 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.🧾 A family uses 120 units of electricity in a month and each unit costs ₹6. What is the bill (in ₹)?
  32. 32.📏 How many watts (W) is 0.6 kW?
  33. 33.True or false: an LDR senses how bright it is. (a) True (b) False
  34. 34.What does a fuse do? (a) blows if current is high (b) has coloured bands (c) senses how hot it is (d) beeps for an alarm
  35. 35.🔺 A 30 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  36. 36.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I + R (c) V = I × R (d) V = I ÷ R
  37. 37.⚡ A 1.5 W device works on 3 V. What current does it take (in amperes)? =
  38. 38.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  39. 39.🔺 A current of 1 A flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
  40. 40.📏 Which unit measures how much a part resists? (a) ampere (A) (b) volt (V) (c) ohm (Ω) (d) watt (W)

Answer key

  1. 20
  2. 38
  3. 20
  4. 81
  5. 1
  6. 130
  7. 2300
  8. 110
  9. 2
  10. 5 %
  11. 1.1
  12. motor
  13. 455
  14. 6
  15. 730
  16. the flow of water
  17. lights up
  18. 40
  19. 15
  20. 137
  21. 66
  22. 50
  23. ammeter
  24. 20
  25. 3400
  26. motor
  27. to limit the current
  28. 5
  29. 7.5
  30. 1.6
  31. 720
  32. 600
  33. True
  34. blows if current is high
  35. 1.5
  36. V = I × R
  37. 0.5
  38. cathode (−)
  39. 4
  40. ohm (Ω)

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