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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 970 · 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: the voltmeter measures current. (a) True (b) False
  2. 2.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
  3. 3.True or false: the ammeter measures current. (a) True (b) False
  4. 4.🔺 A current of 25 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  5. 5.⚡ Power tells us … (a) the colour of light (b) energy used each second (c) the length of a wire (d) the size of a cell
  6. 6.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  7. 7.📏 Which unit measures the flow of charge? (a) ohm (Ω) (b) ampere (A) (c) watt (W) (d) volt (V)
  8. 8.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1000 (b) 1024 (c) 100 (d) 10
  9. 9.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a diode (c) a capacitor (d) a buzzer
  10. 10.🔺 A current of 25 mA flows when 3.75 V is joined across a resistor. What is its resistance (in ohms)?
  11. 11.🧾 A family uses 20 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
  12. 12.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  13. 13.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  14. 14.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = V × I (d) P = I ÷ V
  15. 15.🧮 Resistors of 20 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
  16. 16.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 12 Ω resistor? (a) brown-red-brown (b) brown-red-black (c) red-red-black (d) red-brown-black
  17. 17.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) zero (c) bigger (d) smaller
  18. 18.🧩 Which component smooths a wobbly supply? (a) LED (b) diode (c) capacitor (d) thermistor
  19. 19.Which of these wastes electricity? (a) use old filament bulbs (b) use LED lamps (c) use daylight to read (d) switch off empty rooms
  20. 20.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = R ÷ I (c) V = I × R (d) V = I + R
  21. 21.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
  22. 22.🔺 A 10 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
  23. 23.True or false: to leave the TV on standby saves electricity. (a) True (b) False
  24. 24.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) any band (c) the widest gap (d) the gold band
  25. 25.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  26. 26.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  27. 27.🧾 A 100 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
  28. 28.Which of these saves electricity? (a) leave fridge door open (b) run fans in empty rooms (c) iron one shirt at a time (d) unplug idle chargers
  29. 29.🔺 A current of 50 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.🔺 A 6 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  31. 31.⚡ A device works on 24 V and takes 0.5 A. What is its power (in watts)? =
  32. 32.🔺 A 2 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  33. 33.🔺 In the V-I-R triangle, how do we find R? (a) R = V ÷ I (b) R = V + I (c) R = I ÷ V (d) R = V × I
  34. 34.⚡ A device works on 12 V and takes 0.2 A. What is its power (in watts)? =
  35. 35.🌈 A resistor has the colour bands white, green, yellow. What is its value in kilo-ohms (kΩ)? =
  36. 36.📏 Which unit measures current? (a) volt (V) (b) ampere (A) (c) watt (W) (d) ohm (Ω)
  37. 37.🔺 A current of 3 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  38. 38.True or false: current is measured in amperes (A). (a) True (b) False
  39. 39.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
  40. 40.⚡ A 36 W device works on 24 V. What current does it take (in amperes)? =

Answer key

  1. False
  2. False
  3. True
  4. 5
  5. energy used each second
  6. 20
  7. ampere (A)
  8. 1000
  9. a buzzer
  10. 150
  11. 140
  12. 10
  13. anode (+)
  14. P = V × I
  15. 70
  16. brown-red-black
  17. bigger
  18. capacitor
  19. use old filament bulbs
  20. V = I × R
  21. 115
  22. 50
  23. False
  24. the one nearest an end
  25. cathode (−)
  26. 5
  27. 0.8
  28. unplug idle chargers
  29. 6
  30. 40
  31. 12
  32. 0.1
  33. R = V ÷ I
  34. 2.4
  35. 950
  36. ampere (A)
  37. 45
  38. True
  39. True
  40. 1.5

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