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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 598 · 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 resistor colour code, which number does yellow stand for?
  2. 2.🔺 A current of 0.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  3. 3.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 700 Ω resistor? (a) violet-black-black (b) violet-black-red (c) grey-violet-brown (d) violet-black-brown
  4. 4.🧩 Which component has coloured bands? (a) resistor (b) potentiometer (c) LED (d) diode
  5. 5.🧮 Four equal 400 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  6. 6.Which of these wastes electricity? (a) close the fridge quickly (b) use daylight to read (c) unplug idle chargers (d) leave fridge door open
  7. 7.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 4.25 V supply. What current flows (in mA)?
  8. 8.🧩 Which part changes electrical energy into movement? (a) a resistor (b) a motor (c) a fuse (d) an LED
  9. 9.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 50 % (c) 5 % (d) 25 %
  10. 10.⚡ A device works on 24 V and takes 0.5 A. What is its power (in watts)? =
  11. 11.⚡ A 6 W device works on 24 V. What current does it take (in amperes)? =
  12. 12.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  13. 13.💡 Does it save or waste electricity to run fans in empty rooms? (a) wastes electricity (b) saves electricity
  14. 14.🧾 Which lamp gives the same light for the least power? (a) an oil lamp (b) a candle (c) an LED lamp (d) a filament bulb
  15. 15.What does a diode do? (a) lets current go one way (b) beeps for an alarm (c) makes things spin (d) smooths a wobbly supply
  16. 16.True or false: on an LED, the round-side leg is the anode (+). (a) True (b) False
  17. 17.🔺 A current of 40 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  18. 18.True or false: a resistor has coloured bands. (a) False (b) True
  19. 19.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = I ÷ V (c) R = V ÷ I (d) R = V + I
  20. 20.What does a resistor do? (a) makes a beeping sound (b) lets current go one way (c) glows using little power (d) has coloured bands
  21. 21.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) False (b) True
  22. 22.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 2.75 V supply. What current flows (in mA)?
  23. 23.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I + R (c) V = I × R (d) V = I ÷ R
  24. 24.🔺 A current of 40 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.🔺 A current of 1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  26. 26.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
  27. 27.🌈 A resistor has the colour bands grey, orange, yellow. What is its value in kilo-ohms (kΩ)? =
  28. 28.💡 Does it save or waste electricity to unplug idle chargers? (a) saves electricity (b) wastes electricity
  29. 29.What does a potentiometer do? (a) stores a little charge (b) beeps for an alarm (c) lets current go one way (d) is a resistance knob
  30. 30.🔍 Which is the odd one out? (a) switch off empty rooms (b) use LED lamps (c) use old filament bulbs (d) set the AC to 24 °C
  31. 31.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 30000 Ω resistor? (a) orange-black-orange (b) orange-black-yellow (c) yellow-orange-orange (d) orange-black-red
  32. 32.🔺 A 15 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  33. 33.🧩 Which component senses how hot it is? (a) resistor (b) fuse (c) thermistor (d) capacitor
  34. 34.🔺 A 0.8 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  35. 35.🔺 A current of 40 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = I ÷ V (c) P = V × I (d) P = V + I
  37. 37.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  38. 38.🔺 A current of 25 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  39. 39.⚡ A 2.5 W device works on 5 V. What current does it take (in amperes)? =
  40. 40.🔺 A current of 50 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =

Answer key

  1. 4
  2. 3
  3. violet-black-brown
  4. resistor
  5. 100
  6. leave fridge door open
  7. 15
  8. a motor
  9. 5 %
  10. 12
  11. 0.25
  12. 165
  13. wastes electricity
  14. an LED lamp
  15. lets current go one way
  16. True
  17. 10
  18. True
  19. R = V ÷ I
  20. has coloured bands
  21. True
  22. 5
  23. V = I × R
  24. 18.8
  25. 12
  26. True
  27. 830
  28. saves electricity
  29. is a resistance knob
  30. use old filament bulbs
  31. orange-black-orange
  32. 1.5
  33. thermistor
  34. 0.2
  35. 16
  36. P = V × I
  37. 110
  38. 5.5
  39. 0.5
  40. 15

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