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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 169 · 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.

NameDateTime takenScore ___ / 40
  1. 1.🧩 A capacitor in a circuit can … (a) make light (b) spin a wheel (c) store charge briefly (d) measure heat
  2. 2.⚡ A 12 W device works on 24 V. What current does it take (in amperes)? =
  3. 3.📏 In the water-pipe picture of a circuit, voltage is like … (a) the water pressure (b) the water tank lid (c) the tap handle (d) the pipe colour
  4. 4.🔺 A current of 50 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  5. 5.🔺 A current of 40 mA flows when 12 V is joined across a resistor. What is its resistance (in ohms)?
  6. 6.📏 How many watts (W) is 0.2 kW?
  7. 7.True or false: an LDR senses how bright it is. (a) True (b) False
  8. 8.🧩 Which component turns a fan or wheels? (a) motor (b) capacitor (c) LDR (d) potentiometer
  9. 9.What does a resistor do? (a) is a resistance knob (b) limits the current (c) smooths a wobbly supply (d) makes a beeping sound
  10. 10.🔺 A 30 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  11. 11.⚡ A 27 W device works on 9 V. What current does it take (in amperes)? =
  12. 12.📏 How many amperes (A) is 1710 mA? =
  13. 13.🔍 Which is the odd one out? (a) run fans in empty rooms (b) close the fridge quickly (c) use old filament bulbs (d) leave the TV on standby
  14. 14.🔺 A current of 1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.🧮 A 6 V battery is joined to 8 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
  16. 16.🌈 Which band is read first on a resistor? (a) the gold band (b) the one nearest an end (c) the widest gap (d) any band
  17. 17.🔺 A current of 0.25 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  18. 18.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  19. 19.🔺 A 12 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
  20. 20.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  21. 21.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) False (b) True
  22. 22.🔺 A 0.4 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  23. 23.🔺 A current of 0.5 A flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
  24. 24.🔺 A 4 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  25. 25.🧮 Five equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  26. 26.🔺 A current of 2 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  27. 27.🔍 Which is the odd one out? (a) use daylight to read (b) set the AC to 24 °C (c) switch off empty rooms (d) leave fridge door open
  28. 28.🌈 A resistor has the colour bands grey, white, red. What is its value (in ohms)?
  29. 29.🔺 A current of 40 mA flows when 18.8 V is joined across a resistor. What is its resistance (in ohms)?
  30. 30.True or false: on an LED, the longer leg is the anode (+). (a) False (b) True
  31. 31.⚡ Power tells us … (a) the size of a cell (b) the colour of light (c) energy used each second (d) the length of a wire
  32. 32.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
  33. 33.🧮 Resistors of 150 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
  34. 34.🧩 Which part changes electrical energy into movement? (a) a fuse (b) an LED (c) a motor (d) a resistor
  35. 35.🔺 A 1.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  36. 36.Which of these wastes electricity? (a) unplug idle chargers (b) run fans in empty rooms (c) use daylight to read (d) set the AC to 24 °C
  37. 37.🔺 A 10 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
  38. 38.🧩 Which part changes electrical energy into sound? (a) a buzzer (b) a capacitor (c) a resistor (d) a diode
  39. 39.📏 How many kilo-ohms (kΩ) is 9500 Ω? =
  40. 40.True or false: the voltmeter measures current. (a) True (b) False

Answer key

  1. store charge briefly
  2. 0.5
  3. the water pressure
  4. 12.5
  5. 300
  6. 200
  7. True
  8. motor
  9. limits the current
  10. 2
  11. 3
  12. 1.71
  13. close the fridge quickly
  14. 2
  15. 0.5
  16. the one nearest an end
  17. 2.5
  18. anode (+)
  19. 40
  20. anode (+)
  21. True
  22. 0.1
  23. 5
  24. 1
  25. 10
  26. 12
  27. leave fridge door open
  28. 8900
  29. 470
  30. True
  31. energy used each second
  32. 920
  33. 172
  34. a motor
  35. 0.1
  36. run fans in empty rooms
  37. 50
  38. a buzzer
  39. 9.5
  40. False

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