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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 175 · 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 1.5 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  2. 2.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 5 V supply. What current flows (in mA)?
  3. 3.📏 In the water-pipe picture of a circuit, current is like … (a) the water pressure (b) the flow of water (c) the pipe colour (d) a narrow pipe
  4. 4.📏 How many kilowatts (kW) is 2600 W? =
  5. 5.Which of these wastes electricity? (a) use LED lamps (b) use daylight to read (c) run fans in empty rooms (d) switch off empty rooms
  6. 6.⚡ A device works on 5 V and takes 1.5 A. What is its power (in watts)? =
  7. 7.True or false: the ammeter is joined in series. (a) True (b) False
  8. 8.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 volt (c) 1 ampere (d) 1 kilowatt-hour (kWh)
  9. 9.🔺 A current of 3 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  10. 10.💡 A red LED uses 2 V and should get 10 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
  11. 11.🧾 A family uses 160 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
  12. 12.Which of these saves electricity? (a) leave fridge door open (b) use old filament bulbs (c) iron one shirt at a time (d) set the AC to 24 °C
  13. 13.🔺 A current of 40 mA flows when 8 V is joined across a resistor. What is its resistance (in ohms)?
  14. 14.🧮 Resistors of 10 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
  15. 15.🧮 A 470 Ω resistor is joined in series with two equal 100 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  16. 16.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
  17. 17.🔺 A current of 1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  18. 18.📏 Which unit measures the push of a cell? (a) watt (W) (b) ohm (Ω) (c) ampere (A) (d) volt (V)
  19. 19.🔺 A current of 25 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 10 (b) 1024 (c) 1000 (d) 100
  21. 21.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 25 % (d) 5 %
  22. 22.True or false: how much a part resists is measured in ohms (Ω). (a) False (b) True
  23. 23.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
  24. 24.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  25. 25.🔺 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
  26. 26.🌈 A resistor has the colour bands green, blue, black. What is its value (in ohms)?
  27. 27.🧮 Three equal 60 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  28. 28.🧮 A 3 V battery is joined to 8 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
  29. 29.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) gets smaller (c) stays the same (d) becomes zero
  30. 30.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it changes colour (c) it lights brighter (d) it does not light
  31. 31.🧩 A capacitor in a circuit can … (a) store charge briefly (b) measure heat (c) spin a wheel (d) make light
  32. 32.Which of these is measured in volts (V)? (a) power (b) the push of a cell (c) current (d) the flow of charge
  33. 33.🔺 A current of 0.1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  34. 34.🔺 A current of 0.2 A flows when 0.8 V is joined across a resistor. What is its resistance (in ohms)?
  35. 35.🧾 A 1500 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
  36. 36.🔍 Which is the odd one out? (a) run fans in empty rooms (b) unplug idle chargers (c) close the fridge quickly (d) use LED lamps
  37. 37.📏 How many kilo-ohms (kΩ) is 4300 Ω? =
  38. 38.🔺 An 11 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
  39. 39.⚡ A device works on 1.5 V and takes 1.5 A. What is its power (in watts)? =
  40. 40.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a resistor (c) a diode (d) a buzzer

Answer key

  1. 2
  2. 15
  3. the flow of water
  4. 2.6
  5. run fans in empty rooms
  6. 7.5
  7. True
  8. 1 kilowatt-hour (kWh)
  9. 30
  10. 700
  11. 640
  12. set the AC to 24 °C
  13. 200
  14. 30
  15. 520
  16. False
  17. 2
  18. volt (V)
  19. 2.5
  20. 1000
  21. 5 %
  22. True
  23. 115
  24. anode (+)
  25. V = I × R
  26. 56
  27. 20
  28. 0.25
  29. gets smaller
  30. it does not light
  31. store charge briefly
  32. the push of a cell
  33. 2
  34. 4
  35. 7.5
  36. run fans in empty rooms
  37. 4.3
  38. 50
  39. 2.25
  40. a buzzer

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