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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 341 · 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.🔺 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
  2. 2.🧩 Which component is a resistance knob? (a) fuse (b) potentiometer (c) resistor (d) diode
  3. 3.🧮 A 22 Ω resistor is joined in series with two equal 50 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  4. 4.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) their sum (c) more than either one (d) always zero
  5. 5.🔺 A current of 20 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.🔺 A current of 25 mA flows when 3.75 V is joined across a resistor. What is its resistance (in ohms)?
  7. 7.Which of these saves electricity? (a) leave the TV on standby (b) iron one shirt at a time (c) use LED lamps (d) leave fridge door open
  8. 8.🔺 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
  9. 9.What does a resistor do? (a) beeps for an alarm (b) senses how hot it is (c) makes things spin (d) limits the current
  10. 10.🔺 A 16 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  11. 11.🔺 A current of 50 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  12. 12.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 65000 Ω resistor? (a) blue-green-red (b) blue-green-yellow (c) blue-green-orange (d) green-blue-orange
  13. 13.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a diode (c) a capacitor (d) a buzzer
  14. 14.🧮 A 0.7 V battery is joined to 4 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
  15. 15.True or false: to unplug idle chargers wastes electricity. (a) False (b) True
  16. 16.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  17. 17.True or false: on an LED, the shorter leg is the anode (+). (a) True (b) False
  18. 18.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
  19. 19.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 42 Ω resistor? (a) green-red-black (b) red-yellow-black (c) yellow-red-black (d) yellow-red-brown
  20. 20.🧮 Resistors of 20 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
  21. 21.📏 How many amperes (A) is 1180 mA? =
  22. 22.🔺 An 8 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  23. 23.🔺 A 4.7 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  24. 24.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) an oil lamp (c) a candle (d) an LED lamp
  25. 25.📏 Which unit measures the push of a cell? (a) ohm (Ω) (b) watt (W) (c) volt (V) (d) ampere (A)
  26. 26.🧮 A 1 V battery is joined to 2 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
  27. 27.🔺 In the V-I-R triangle, how do we find I? (a) I = V ÷ R (b) I = V × R (c) I = V + R (d) I = R ÷ V
  28. 28.📏 Which unit measures energy used each second? (a) watt (W) (b) ampere (A) (c) ohm (Ω) (d) volt (V)
  29. 29.Which of these wastes electricity? (a) unplug idle chargers (b) use old filament bulbs (c) switch off empty rooms (d) use daylight to read
  30. 30.💡 Why does an LED need a resistor in series? (a) to store charge (b) to limit the current (c) to make it brighter (d) to change its colour
  31. 31.🧾 A family uses 80 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
  32. 32.🔺 A 2 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  33. 33.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  34. 34.🔍 Which is the odd one out? (a) use LED lamps (b) unplug idle chargers (c) iron one shirt at a time (d) set the AC to 24 °C
  35. 35.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
  36. 36.🌈 A resistor has the colour bands green, grey, red. What is its value (in ohms)?
  37. 37.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  38. 38.🧮 Five equal 500 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  39. 39.📏 In the water-pipe picture of a circuit, current is like … (a) the pipe colour (b) the water pressure (c) a narrow pipe (d) the flow of water
  40. 40.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = I ÷ V (c) P = V × I (d) P = V + I

Answer key

  1. R = V ÷ I
  2. potentiometer
  3. 47
  4. less than either one
  5. 2.4
  6. 150
  7. use LED lamps
  8. V = I × R
  9. limits the current
  10. 40
  11. 20
  12. blue-green-orange
  13. a buzzer
  14. 0.1
  15. False
  16. 10
  17. False
  18. 230
  19. yellow-red-black
  20. 42
  21. 1.18
  22. 1
  23. 10
  24. an LED lamp
  25. volt (V)
  26. 0.1
  27. I = V ÷ R
  28. watt (W)
  29. use old filament bulbs
  30. to limit the current
  31. 320
  32. 0.5
  33. cathode (−)
  34. iron one shirt at a time
  35. 1840
  36. 5800
  37. 80
  38. 100
  39. the flow of water
  40. P = V × I

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