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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 28 · 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.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 6 hours. How many watt-hours (Wh) are saved?
  2. 2.💡 An LED is joined to a 5 V battery with no 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
  3. 3.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 76000 Ω resistor? (a) violet-blue-red (b) blue-violet-orange (c) violet-blue-yellow (d) violet-blue-orange
  4. 4.💡 Does it save or waste electricity to switch off empty rooms? (a) saves electricity (b) wastes electricity
  5. 5.🧮 A 150 Ω resistor is joined in series with two equal 100 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  6. 6.🔺 A current of 25 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  7. 7.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
  8. 8.True or false: to use daylight to read saves electricity. (a) False (b) True
  9. 9.🔺 A current of 1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  10. 10.True or false: to close the fridge quickly saves electricity. (a) True (b) False
  11. 11.💡 A red LED uses 2 V and should get 10 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
  12. 12.🧾 A 250 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
  13. 13.True or false: resistance is measured in volts (V). (a) True (b) False
  14. 14.📏 How many amperes (A) is 1570 mA? =
  15. 15.🔺 A current of 0.1 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  16. 16.🌈 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
  17. 17.🧩 Which component senses how hot it is? (a) diode (b) thermistor (c) LED (d) potentiometer
  18. 18.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) stays the same (c) gets bigger (d) gets smaller
  19. 19.🔺 A current of 25 mA flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  20. 20.📏 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
  21. 21.📏 How many kilowatts (kW) is 4400 W? =
  22. 22.📏 Which unit measures voltage? (a) ohm (Ω) (b) ampere (A) (c) watt (W) (d) volt (V)
  23. 23.🔺 A current of 20 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  24. 24.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 50 % (c) 0 % (d) 25 %
  25. 25.True or false: to use daylight to read wastes electricity. (a) True (b) False
  26. 26.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 80000 Ω resistor? (a) grey-black-yellow (b) white-grey-orange (c) grey-black-orange (d) grey-black-red
  27. 27.🔺 A current of 0.1 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  28. 28.⚡ A 6 W device works on 12 V. What current does it take (in amperes)? =
  29. 29.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
  30. 30.🔺 A current of 3 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.🧾 A family uses 130 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
  32. 32.🧾 A family uses 50 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
  33. 33.⚡ Which formula gives electric power? (a) P = V + I (b) P = V × I (c) P = I ÷ V (d) P = V ÷ I
  34. 34.🧮 A 1 V battery is joined to 8 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
  35. 35.True or false: on an LED, the longer leg is the anode (+). (a) True (b) False
  36. 36.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
  37. 37.🧮 A 4 V battery is joined to 8 Ω and 12 Ω resistors in series. What current flows (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.🧮 Two resistors in parallel give a total that is … (a) always zero (b) their sum (c) less than either one (d) more than either one
  40. 40.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?

Answer key

  1. 510
  2. may burn out
  3. violet-blue-orange
  4. saves electricity
  5. 200
  6. 6.25
  7. False
  8. True
  9. 3
  10. True
  11. 700
  12. 2
  13. False
  14. 1.57
  15. 1
  16. the one nearest an end
  17. thermistor
  18. gets smaller
  19. 120
  20. the flow of water
  21. 4.4
  22. volt (V)
  23. 8
  24. 5 %
  25. False
  26. grey-black-orange
  27. 1.5
  28. 0.5
  29. False
  30. 9
  31. 520
  32. 350
  33. P = V × I
  34. 0.1
  35. True
  36. 920
  37. 0.2
  38. cathode (−)
  39. less than either one
  40. 20

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