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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 166 · 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.🔺 A current of 20 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  2. 2.📏 Which unit measures voltage? (a) watt (W) (b) ohm (Ω) (c) volt (V) (d) ampere (A)
  3. 3.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 50 % (c) 25 % (d) 0 %
  4. 4.🔺 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
  5. 5.True or false: the ammeter measures voltage. (a) True (b) False
  6. 6.🔺 A current of 2.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  7. 7.🔍 Which is the odd one out? (a) close the fridge quickly (b) unplug idle chargers (c) switch off empty rooms (d) leave fridge door open
  8. 8.🧮 Five equal 25 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  9. 9.🔺 A 1.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  10. 10.🔺 A current of 25 mA flows when 11.75 V is joined across a resistor. What is its resistance (in ohms)?
  11. 11.🔺 A current of 0.1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  12. 12.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
  13. 13.🔺 A current of 3 A flows when 30 V is joined across a resistor. What is its resistance (in ohms)?
  14. 14.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 1 hour. How many watt-hours (Wh) are saved?
  15. 15.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3 V supply. What current flows (in mA)?
  16. 16.Which of these is measured in amperes (A)? (a) energy used each second (b) how much a part resists (c) resistance (d) the flow of charge
  17. 17.🌈 A resistor has the colour bands violet, brown, brown. What is its value (in ohms)?
  18. 18.🧮 A 4.5 V battery is joined to 3 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
  19. 19.What does a diode do? (a) lets current go one way (b) glows using little power (c) senses how bright it is (d) beeps for an alarm
  20. 20.🧾 A 50 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
  21. 21.🧩 Which component makes a beeping sound? (a) buzzer (b) LDR (c) capacitor (d) LED
  22. 22.True or false: to use LED lamps wastes electricity. (a) True (b) False
  23. 23.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
  24. 24.📏 In the water-pipe picture of a circuit, voltage is like … (a) the tap handle (b) the water pressure (c) the pipe colour (d) the water tank lid
  25. 25.🧾 A family uses 140 units of electricity in a month and each unit costs ₹9. What is the bill (in ₹)?
  26. 26.🔺 A 10 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  27. 27.💡 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?
  28. 28.🔺 A current of 1 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  29. 29.🧮 Four equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  30. 30.🧮 A 1.2 V battery is joined to 4 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
  31. 31.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  32. 32.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  33. 33.True or false: an LDR senses how bright it is. (a) True (b) False
  34. 34.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) a candle (c) an LED lamp (d) an oil lamp
  35. 35.True or false: the voltmeter measures current. (a) True (b) False
  36. 36.🧩 Which part changes electrical energy into movement? (a) a fuse (b) a resistor (c) an LED (d) a motor
  37. 37.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 67000 Ω resistor? (a) violet-blue-orange (b) blue-violet-yellow (c) blue-violet-red (d) blue-violet-orange
  38. 38.🔺 A current of 20 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  39. 39.🔺 A current of 25 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  40. 40.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =

Answer key

  1. 8
  2. volt (V)
  3. 5 %
  4. V = I × R
  5. False
  6. 30
  7. leave fridge door open
  8. 5
  9. 0.1
  10. 470
  11. 0.3
  12. 920
  13. 10
  14. 85
  15. 10
  16. the flow of charge
  17. 710
  18. 0.5
  19. lets current go one way
  20. 0.1
  21. buzzer
  22. False
  23. ammeter
  24. the water pressure
  25. 1260
  26. 0.5
  27. 120
  28. 15
  29. 25
  30. 0.1
  31. cathode (−)
  32. 110
  33. True
  34. an LED lamp
  35. False
  36. a motor
  37. blue-violet-orange
  38. 10
  39. 10
  40. 1

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