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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 195 · 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.Which of these saves electricity? (a) run fans in empty rooms (b) use old filament bulbs (c) switch off empty rooms (d) leave fridge door open
  2. 2.🔺 A 12.5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
  3. 3.True or false: the push of a cell is measured in volts (V). (a) False (b) True
  4. 4.🔺 A 1 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  5. 5.🧾 Which lamp gives the same light for the least power? (a) an LED lamp (b) a candle (c) a filament bulb (d) an oil lamp
  6. 6.💡 Does it save or waste electricity to iron one shirt at a time? (a) wastes electricity (b) saves electricity
  7. 7.🔺 A 1.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  8. 8.Which of these saves electricity? (a) run fans in empty rooms (b) iron one shirt at a time (c) use LED lamps (d) use old filament bulbs
  9. 9.📏 How many amperes (A) is 2510 mA? =
  10. 10.🔺 A current of 0.25 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  11. 11.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  12. 12.💡 Does it save or waste electricity to set the AC to 24 °C? (a) saves electricity (b) wastes electricity
  13. 13.🧾 A 1000 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
  14. 14.Which of these wastes electricity? (a) set the AC to 24 °C (b) unplug idle chargers (c) use daylight to read (d) use old filament bulbs
  15. 15.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
  16. 16.🔺 A current of 50 mA flows when 25 V is joined across a resistor. What is its resistance (in ohms)?
  17. 17.💡 An LED is joined to a 5 V battery through a 470 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) lights up (b) may burn out (c) does not light
  18. 18.🔺 A current of 2.5 A flows when 30 V is joined across a resistor. What is its resistance (in ohms)?
  19. 19.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
  20. 20.True or false: the ammeter is joined in series. (a) True (b) False
  21. 21.🧮 A 33 Ω resistor is joined in series with two equal 220 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  22. 22.🔺 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
  23. 23.🧮 A 100 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  24. 24.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  25. 25.🔺 A current of 2.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  26. 26.🔺 A current of 3 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  27. 27.🔺 A current of 0.25 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  28. 28.🌈 Which band is read first on a resistor? (a) the widest gap (b) any band (c) the one nearest an end (d) the gold band
  29. 29.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
  30. 30.⚡ 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
  31. 31.🔺 A 2 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  32. 32.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1000 (b) 100 (c) 10 (d) 1024
  33. 33.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 65000 Ω resistor? (a) blue-green-red (b) blue-green-orange (c) green-blue-orange (d) blue-green-yellow
  34. 34.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
  35. 35.🧩 Which part changes electrical energy into movement? (a) a fuse (b) a motor (c) a resistor (d) an LED
  36. 36.🔺 In the V-I-R triangle, how do we find V? (a) V = I × R (b) V = I + R (c) V = R ÷ I (d) V = I ÷ R
  37. 37.📏 How many kilo-ohms (kΩ) is 6700 Ω? =
  38. 38.True or false: a buzzer has coloured bands. (a) False (b) True
  39. 39.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  40. 40.🔺 A 5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?

Answer key

  1. switch off empty rooms
  2. 50
  3. True
  4. 0.2
  5. an LED lamp
  6. wastes electricity
  7. 10
  8. use LED lamps
  9. 2.51
  10. 8
  11. 165
  12. saves electricity
  13. 5
  14. use old filament bulbs
  15. voltmeter
  16. 500
  17. lights up
  18. 12
  19. 120
  20. True
  21. 143
  22. gets smaller
  23. 105
  24. 20
  25. 25
  26. 24
  27. 3.75
  28. the one nearest an end
  29. 1840
  30. energy used each second
  31. 0.25
  32. 1000
  33. blue-green-orange
  34. 300
  35. a motor
  36. V = I × R
  37. 6.7
  38. False
  39. 1
  40. 20

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