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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 543 · 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 formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = V × I (d) P = I ÷ V
  2. 2.🧾 A family uses 30 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
  3. 3.🔺 A 0.8 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  4. 4.⚡ Power tells us … (a) the size of a cell (b) the length of a wire (c) the colour of light (d) energy used each second
  5. 5.📏 How many milliamperes (mA) is 1.72 A?
  6. 6.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it does not light (c) it lights brighter (d) it changes colour
  7. 7.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
  8. 8.🧩 Which part changes electrical energy into movement? (a) a resistor (b) an LED (c) a motor (d) a fuse
  9. 9.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) bigger (c) smaller (d) zero
  10. 10.📏 How many watts (W) is 3.3 kW?
  11. 11.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V × I (c) R = V + I (d) R = V ÷ I
  12. 12.🧮 A 10 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)?
  13. 13.⚡ A device works on 12 V and takes 3 A. What is its power (in watts)? =
  14. 14.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 10 hours. How many watt-hours (Wh) are saved?
  15. 15.🔺 A current of 10 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  16. 16.True or false: the voltmeter is joined in series. (a) False (b) True
  17. 17.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 82000 Ω resistor? (a) grey-red-red (b) grey-red-yellow (c) red-grey-orange (d) grey-red-orange
  18. 18.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  19. 19.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) the gold band (c) the widest gap (d) any band
  20. 20.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
  21. 21.🧩 A capacitor in a circuit can … (a) store charge briefly (b) spin a wheel (c) measure heat (d) make light
  22. 22.🔺 A current of 40 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.📏 How many milliamperes (mA) is 2.19 A?
  24. 24.🔺 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
  25. 25.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) their sum (c) more than either one (d) always zero
  26. 26.🔺 A current of 1.5 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  27. 27.True or false: voltage is measured in ohms (Ω). (a) True (b) False
  28. 28.🔍 Which is the odd one out? (a) unplug idle chargers (b) use LED lamps (c) close the fridge quickly (d) iron one shirt at a time
  29. 29.⚡ A device works on 9 V and takes 1 A. What is its power (in watts)? =
  30. 30.⚡ A device works on 24 V and takes 1.5 A. What is its power (in watts)? =
  31. 31.🔺 A current of 50 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  32. 32.True or false: a capacitor stores a little charge. (a) True (b) False
  33. 33.True or false: to run fans in empty rooms wastes electricity. (a) False (b) True
  34. 34.🔺 A 6 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  35. 35.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
  36. 36.🧮 A 22 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)?
  37. 37.📏 In the water-pipe picture of a circuit, current is like … (a) a narrow pipe (b) the flow of water (c) the pipe colour (d) the water pressure
  38. 38.🔺 A current of 50 mA flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
  39. 39.🧩 Which component senses how bright it is? (a) diode (b) resistor (c) LED (d) LDR
  40. 40.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 6 V supply. What current flows (in mA)?

Answer key

  1. P = V × I
  2. 120
  3. 0.2
  4. energy used each second
  5. 1720
  6. it does not light
  7. voltmeter
  8. a motor
  9. bigger
  10. 3300
  11. R = V ÷ I
  12. 35
  13. 36
  14. 510
  15. 1.5
  16. False
  17. grey-red-orange
  18. cathode (−)
  19. the one nearest an end
  20. 300
  21. store charge briefly
  22. 8.8
  23. 2190
  24. V = I × R
  25. less than either one
  26. 4
  27. False
  28. iron one shirt at a time
  29. 9
  30. 36
  31. 15
  32. True
  33. True
  34. 2
  35. 1150
  36. 257
  37. the flow of water
  38. 150
  39. LDR
  40. 20

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