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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 694 · 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.

NameDateTime takenScore ___ / 40
  1. 1.True or false: power is measured in amperes (A). (a) False (b) True
  2. 2.⚡ A 6 W device works on 6 V. What current does it take (in amperes)? =
  3. 3.🧮 A 4 V battery is joined to 8 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
  4. 4.🧾 A family uses 20 units of electricity in a month and each unit costs ₹9. What is the bill (in ₹)?
  5. 5.⚡ A device works on 24 V and takes 0.1 A. What is its power (in watts)? =
  6. 6.🧮 Resistors of 100 Ω, 50 Ω, 150 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
  7. 7.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  8. 8.🔺 A current of 0.2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  9. 9.🔺 A current of 50 mA flows when 25 V is joined across a resistor. What is its resistance (in ohms)?
  10. 10.True or false: power is measured in ohms (Ω). (a) True (b) False
  11. 11.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  12. 12.True or false: to set the AC to 24 °C wastes electricity. (a) True (b) False
  13. 13.🔺 A current of 0.25 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.🧮 A 1 V battery is joined to 2 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
  15. 15.🔺 A current of 0.2 A flows when 0.8 V is joined across a resistor. What is its resistance (in ohms)?
  16. 16.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
  17. 17.💡 An LED is joined to a 3 V battery through a 220 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) may burn out (c) lights up
  18. 18.🧮 Resistors of 100 Ω, 20 Ω, 220 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
  19. 19.🔺 A current of 40 mA flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
  20. 20.💡 Does it save or waste electricity to use LED lamps? (a) wastes electricity (b) saves electricity
  21. 21.⚡ A device works on 5 V and takes 0.25 A. What is its power (in watts)? =
  22. 22.🔺 A current of 0.1 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.🧮 A 68 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)?
  24. 24.🔺 A 12.5 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  25. 25.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 10 hours. How many watt-hours (Wh) are saved?
  26. 26.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
  27. 27.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets bigger (c) gets smaller (d) stays the same
  28. 28.True or false: a motor is a resistance knob. (a) True (b) False
  29. 29.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 50 % (c) 25 % (d) 5 %
  30. 30.True or false: resistance is measured in watts (W). (a) False (b) True
  31. 31.🔺 A current of 20 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  32. 32.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V × I (c) P = V ÷ I (d) P = V + I
  33. 33.💡 An LED is joined to a 9 V battery through a 220 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
  34. 34.Which of these is measured in volts (V)? (a) voltage (b) resistance (c) power (d) current
  35. 35.🔺 A 10 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  36. 36.🧩 A capacitor in a circuit can … (a) store charge briefly (b) make light (c) measure heat (d) spin a wheel
  37. 37.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 6800 Ω resistor? (a) grey-blue-red (b) blue-grey-brown (c) blue-grey-orange (d) blue-grey-red
  38. 38.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
  39. 39.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 2.75 V supply. What current flows (in mA)?
  40. 40.⚡ 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

Answer key

  1. False
  2. 1
  3. 0.2
  4. 180
  5. 2.4
  6. 310
  7. 10
  8. 0.6
  9. 500
  10. False
  11. cathode (−)
  12. False
  13. 3.75
  14. 0.2
  15. 4
  16. ammeter
  17. lights up
  18. 387
  19. 500
  20. saves electricity
  21. 1.25
  22. 1.5
  23. 303
  24. 25
  25. 340
  26. 150
  27. gets smaller
  28. False
  29. 5 %
  30. False
  31. 3
  32. P = V × I
  33. does not light
  34. voltage
  35. 25
  36. store charge briefly
  37. blue-grey-red
  38. False
  39. 5
  40. energy used each second

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