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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 509 · 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.True or false: on an LED, the longer leg is the anode (+). (a) True (b) False
  2. 2.🔺 A 23.5 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  3. 3.🧮 Resistors of 20 Ω and 220 Ω are joined in series. What is the total resistance (in ohms)?
  4. 4.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  5. 5.🔺 A current of 25 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.Which of these is measured in volts (V)? (a) resistance (b) power (c) voltage (d) how much a part resists
  7. 7.Which of these is measured in amperes (A)? (a) resistance (b) the flow of charge (c) voltage (d) power
  8. 8.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V × I (c) P = V + I (d) P = V ÷ I
  9. 9.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  10. 10.💡 Does it save or waste electricity to switch off empty rooms? (a) saves electricity (b) wastes electricity
  11. 11.What does an LDR do? (a) beeps for an alarm (b) limits the current (c) makes a beeping sound (d) senses how bright it is
  12. 12.⚡ A device works on 3 V and takes 2 A. What is its power (in watts)? =
  13. 13.🌈 A resistor has the colour bands white, red, brown. What is its value (in ohms)?
  14. 14.💡 A red LED uses 2 V and should get 25 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  15. 15.🔺 A current of 10 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  16. 16.⚡ A device works on 3 V and takes 3 A. What is its power (in watts)? =
  17. 17.📏 How many milliamperes (mA) make 1 ampere? (a) 60 (b) 1000 (c) 100 (d) 10
  18. 18.🧩 Which part changes electrical energy into sound? (a) a buzzer (b) a resistor (c) a capacitor (d) a diode
  19. 19.🧮 Five equal 25 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  20. 20.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
  21. 21.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 kilowatt-hour (kWh) (c) 1 watt (d) 1 ampere
  22. 22.🧾 A family uses 120 units of electricity in a month and each unit costs ₹6. What is the bill (in ₹)?
  23. 23.🔺 A current of 10 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  24. 24.🔺 A current of 50 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
  26. 26.🧾 A 1500 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
  27. 27.🧾 A 50 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
  28. 28.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  29. 29.True or false: the flow of charge is measured in amperes (A). (a) False (b) True
  30. 30.Which of these saves electricity? (a) use daylight to read (b) use old filament bulbs (c) leave the TV on standby (d) iron one shirt at a time
  31. 31.🌈 A resistor has the colour bands violet, blue, red. What is its value (in ohms)?
  32. 32.🔺 A current of 1 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  33. 33.True or false: the voltmeter is joined in series. (a) True (b) False
  34. 34.📏 Which unit measures the flow of charge? (a) watt (W) (b) ampere (A) (c) volt (V) (d) ohm (Ω)
  35. 35.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) the gold band (c) any band (d) the widest gap
  36. 36.📏 In the water-pipe picture of a circuit, resistance is like … (a) the flow of water (b) a bigger tank (c) the water pressure (d) a narrow pipe
  37. 37.🧩 Which part changes electrical energy into movement? (a) a resistor (b) a motor (c) a fuse (d) an LED
  38. 38.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  39. 39.🌈 In the resistor colour code, which number does white stand for?
  40. 40.🧩 A capacitor in a circuit can … (a) store charge briefly (b) spin a wheel (c) make light (d) measure heat

Answer key

  1. True
  2. 50
  3. 240
  4. anode (+)
  5. 3
  6. voltage
  7. the flow of charge
  8. P = V × I
  9. 500
  10. saves electricity
  11. senses how bright it is
  12. 6
  13. 920
  14. 120
  15. 2
  16. 9
  17. 1000
  18. a buzzer
  19. 5
  20. 230
  21. 1 kilowatt-hour (kWh)
  22. 720
  23. 1.5
  24. 23.5
  25. 1840
  26. 9
  27. 0.3
  28. anode (+)
  29. True
  30. use daylight to read
  31. 7600
  32. 3
  33. False
  34. ampere (A)
  35. the one nearest an end
  36. a narrow pipe
  37. a motor
  38. cathode (−)
  39. 9
  40. store charge briefly

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