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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 507 · 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 home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
  2. 2.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  3. 3.💡 A red LED uses 2 V and should get 10 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  4. 4.⚡ Power tells us … (a) the length of a wire (b) the size of a cell (c) energy used each second (d) the colour of light
  5. 5.🧮 A 330 Ω resistor is joined in series with two equal 40 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  6. 6.⚡ A device works on 1.5 V and takes 3 A. What is its power (in watts)? =
  7. 7.🧮 Resistors of 22 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
  8. 8.⚡ Which formula gives electric power? (a) P = V × I (b) P = I ÷ V (c) P = V + I (d) P = V ÷ I
  9. 9.🔺 A current of 0.25 A flows when 1.25 V is joined across a resistor. What is its resistance (in ohms)?
  10. 10.🔺 A current of 50 mA flows when 15 V is joined across a resistor. What is its resistance (in ohms)?
  11. 11.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 690 Ω resistor? (a) blue-white-black (b) white-blue-brown (c) blue-white-brown (d) blue-white-red
  12. 12.🧩 Which component limits the current? (a) fuse (b) potentiometer (c) LDR (d) resistor
  13. 13.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  14. 14.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  15. 15.🧩 Which component has coloured bands? (a) transistor (b) motor (c) capacitor (d) resistor
  16. 16.🔺 A 1.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  17. 17.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 0 % (c) 50 % (d) 5 %
  18. 18.🔺 A 3 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  19. 19.⚡ A 0.15 W device works on 1.5 V. What current does it take (in amperes)? =
  20. 20.💡 Does it save or waste electricity to use old filament bulbs? (a) saves electricity (b) wastes electricity
  21. 21.🔺 A 7.5 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  22. 22.💡 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
  23. 23.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  24. 24.⚡ An 18 W device works on 12 V. What current does it take (in amperes)? =
  25. 25.📏 How many milliamperes (mA) is 1.82 A?
  26. 26.🌈 In the resistor colour code, which number does green stand for?
  27. 27.🌈 A resistor has the colour bands green, red, black. What is its value (in ohms)?
  28. 28.🌈 In the resistor colour code, which number does white stand for?
  29. 29.Which of these is measured in ohms (Ω)? (a) energy used each second (b) current (c) voltage (d) how much a part resists
  30. 30.🧩 Which component blows if current is high? (a) buzzer (b) transistor (c) diode (d) fuse
  31. 31.🧩 Which part changes electrical energy into sound? (a) a buzzer (b) a diode (c) a capacitor (d) a resistor
  32. 32.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
  33. 33.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  34. 34.📏 How many milliamperes (mA) is 1 A?
  35. 35.💡 A red LED uses 2 V and should get 10 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
  36. 36.What does an LED do? (a) senses how bright it is (b) lets current go one way (c) glows using little power (d) senses how hot it is
  37. 37.🔺 A 2 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
  38. 38.True or false: the voltmeter is joined in series. (a) True (b) False
  39. 39.True or false: how much a part resists is measured in ohms (Ω). (a) True (b) False
  40. 40.🔺 A current of 10 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =

Answer key

  1. 1150
  2. cathode (−)
  3. 300
  4. energy used each second
  5. 350
  6. 4.5
  7. 44
  8. P = V × I
  9. 5
  10. 300
  11. blue-white-brown
  12. resistor
  13. 5
  14. cathode (−)
  15. resistor
  16. 10
  17. 5 %
  18. 20
  19. 0.1
  20. wastes electricity
  21. 2.5
  22. to limit the current
  23. anode (+)
  24. 1.5
  25. 1820
  26. 5
  27. 52
  28. 9
  29. how much a part resists
  30. fuse
  31. a buzzer
  32. voltmeter
  33. anode (+)
  34. 1000
  35. 400
  36. glows using little power
  37. 10
  38. False
  39. True
  40. 4.7

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