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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 95 · 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.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
  2. 2.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  3. 3.True or false: to leave the TV on standby saves electricity. (a) True (b) False
  4. 4.⚡ A device works on 5 V and takes 0.1 A. What is its power (in watts)? =
  5. 5.🔍 Which is the odd one out? (a) leave the TV on standby (b) leave fridge door open (c) iron one shirt at a time (d) unplug idle chargers
  6. 6.💡 What happens if an LED is put in backwards? (a) it does not light (b) it lights brighter (c) it makes a sound (d) it changes colour
  7. 7.🧾 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
  8. 8.🧮 A 47 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)?
  9. 9.🔺 A current of 20 mA flows when 8 V is joined across a resistor. What is its resistance (in ohms)?
  10. 10.📏 How many ohms (Ω) is 8.1 kΩ?
  11. 11.🔺 A current of 2 A flows when 8 V is joined across a resistor. What is its resistance (in ohms)?
  12. 12.True or false: the voltmeter is joined across a part. (a) True (b) False
  13. 13.🔺 A current of 0.1 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = V × I (d) P = I ÷ V
  15. 15.True or false: a potentiometer is a resistance knob. (a) False (b) True
  16. 16.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) their sum (c) always zero (d) less than either one
  17. 17.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
  18. 18.What does a capacitor do? (a) glows using little power (b) has coloured bands (c) senses how bright it is (d) stores a little charge
  19. 19.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  20. 20.True or false: on an LED, the round-side leg is the anode (+). (a) True (b) False
  21. 21.🔺 A current of 2.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  22. 22.💡 Why does an LED need a resistor in series? (a) to store charge (b) to limit the current (c) to change its colour (d) to make it brighter
  23. 23.📏 How many milliamperes (mA) is 0.09 A?
  24. 24.💡 Does it save or waste electricity to close the fridge quickly? (a) wastes electricity (b) saves electricity
  25. 25.🌈 A resistor has the colour bands red, red, orange. What is its value (in ohms)?
  26. 26.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  27. 27.🔺 A current of 0.25 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  28. 28.True or false: power is measured in watts (W). (a) False (b) True
  29. 29.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
  30. 30.🔺 A 10 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
  31. 31.🔺 A current of 25 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  32. 32.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  33. 33.🔺 In the V-I-R triangle, how do we find R? (a) R = V + I (b) R = V × I (c) R = I ÷ V (d) R = V ÷ I
  34. 34.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) becomes zero (c) stays the same (d) gets smaller
  35. 35.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  36. 36.📏 How many milliamperes (mA) is 0.86 A?
  37. 37.🌈 In the resistor colour code, which number does white stand for?
  38. 38.🌈 Which band is read first on a resistor? (a) any band (b) the one nearest an end (c) the widest gap (d) the gold band
  39. 39.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 79 Ω resistor? (a) violet-white-brown (b) white-violet-black (c) grey-white-black (d) violet-white-black
  40. 40.What does a potentiometer do? (a) makes things spin (b) stores a little charge (c) blows if current is high (d) is a resistance knob

Answer key

  1. voltmeter
  2. cathode (−)
  3. False
  4. 0.5
  5. unplug idle chargers
  6. it does not light
  7. an LED lamp
  8. 67
  9. 400
  10. 8100
  11. 4
  12. True
  13. 0.6
  14. P = V × I
  15. True
  16. less than either one
  17. False
  18. stores a little charge
  19. 100
  20. True
  21. 20
  22. to limit the current
  23. 90
  24. saves electricity
  25. 22000
  26. anode (+)
  27. 3.75
  28. True
  29. 115
  30. 40
  31. 200
  32. 10
  33. R = V ÷ I
  34. gets smaller
  35. 500
  36. 860
  37. 9
  38. the one nearest an end
  39. violet-white-black
  40. is a resistance knob

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