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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 402 · 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 10 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  2. 2.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  3. 3.🧮 Two resistors in parallel give a total that is … (a) their sum (b) more than either one (c) less than either one (d) always zero
  4. 4.🧾 A family uses 140 units of electricity in a month and each unit costs ₹8. What is the bill (in ₹)?
  5. 5.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 95000 Ω resistor? (a) white-green-orange (b) white-green-red (c) white-green-yellow (d) green-white-orange
  6. 6.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 50 % (c) 5 % (d) 25 %
  7. 7.🔍 Which is the odd one out? (a) use LED lamps (b) use daylight to read (c) switch off empty rooms (d) iron one shirt at a time
  8. 8.📏 How many kilowatts (kW) is 2500 W? =
  9. 9.🔺 A 1 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  10. 10.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a diode (c) a resistor (d) a buzzer
  11. 11.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 2 hours. How many watt-hours (Wh) are saved?
  12. 12.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  13. 13.📏 In the water-pipe picture of a circuit, voltage is like … (a) the water tank lid (b) the tap handle (c) the pipe colour (d) the water pressure
  14. 14.🌈 A resistor has the colour bands blue, yellow, orange. What is its value in kilo-ohms (kΩ)? =
  15. 15.📏 How many ohms (Ω) is 0.3 kΩ?
  16. 16.🔺 A current of 0.1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 3.5 V supply. What current flows (in mA)?
  18. 18.🌈 Which band is read first on a resistor? (a) the widest gap (b) the one nearest an end (c) any band (d) the gold band
  19. 19.🧮 A 150 Ω resistor is joined in series with two equal 20 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  20. 20.🌈 A resistor has the colour bands red, green, red. What is its value in kilo-ohms (kΩ)? =
  21. 21.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) stay the same (c) bigger (d) smaller
  22. 22.🔺 A current of 0.2 A flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
  23. 23.📏 Which unit measures current? (a) ampere (A) (b) watt (W) (c) ohm (Ω) (d) volt (V)
  24. 24.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 46000 Ω resistor? (a) blue-yellow-orange (b) yellow-blue-red (c) yellow-blue-orange (d) yellow-blue-yellow
  25. 25.🔺 A current of 1.5 A flows when 4.5 V is joined across a resistor. What is its resistance (in ohms)?
  26. 26.💡 An LED is joined to a 3 V battery through a 1000 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) lights up (c) does not light
  27. 27.🔺 A 7.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  28. 28.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = I ÷ R (c) V = I × R (d) V = R ÷ I
  29. 29.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
  30. 30.🔺 A current of 0.1 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.🧾 A 2000 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
  32. 32.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V ÷ I (d) P = V × I
  33. 33.🧩 A capacitor in a circuit can … (a) spin a wheel (b) measure heat (c) make light (d) store charge briefly
  34. 34.🔺 A current of 10 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.💡 An LED is joined to a 3 V battery through a 470 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) may burn out (b) lights up (c) does not light
  36. 36.🔺 A current of 20 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  37. 37.🔺 A current of 0.1 A flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
  38. 38.💡 Why does an LED need a resistor in series? (a) to store charge (b) to make it brighter (c) to change its colour (d) to limit the current
  39. 39.🧮 A 7.5 V battery is joined to 3 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
  40. 40.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)

Answer key

  1. 2.5
  2. 500
  3. less than either one
  4. 1120
  5. white-green-orange
  6. 5 %
  7. iron one shirt at a time
  8. 2.5
  9. 0.2
  10. a buzzer
  11. 68
  12. anode (+)
  13. the water pressure
  14. 64
  15. 300
  16. 0.2
  17. 10
  18. the one nearest an end
  19. 160
  20. 2.5
  21. bigger
  22. 5
  23. ampere (A)
  24. yellow-blue-orange
  25. 3
  26. lights up
  27. 50
  28. V = I × R
  29. 1840
  30. 0.8
  31. 20
  32. P = V × I
  33. store charge briefly
  34. 5
  35. does not light
  36. 100
  37. 12
  38. to limit the current
  39. 0.5
  40. anode (+)

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