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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 64 · 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 current of 0.25 A flows when 1.25 V is joined across a resistor. What is its resistance (in ohms)?
  2. 2.🧾 A 1000 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
  3. 3.What does a transistor do? (a) smooths a wobbly supply (b) turns a fan or wheels (c) lets current go one way (d) boosts a small signal
  4. 4.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) gets smaller (c) becomes zero (d) stays the same
  5. 5.🔺 A current of 10 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.⚡ Power tells us … (a) the size of a cell (b) the colour of light (c) the length of a wire (d) energy used each second
  7. 7.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 kilowatt-hour (kWh) (c) 1 volt (d) 1 ampere
  8. 8.🔺 A 1.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  9. 9.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 3 hours. How many watt-hours (Wh) are saved?
  10. 10.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to store charge (c) to make it brighter (d) to change its colour
  11. 11.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a buzzer (c) a resistor (d) a diode
  12. 12.🧩 A capacitor in a circuit can … (a) spin a wheel (b) store charge briefly (c) make light (d) measure heat
  13. 13.🔺 A 2 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  14. 14.🌈 Which band is read first on a resistor? (a) the widest gap (b) any band (c) the gold band (d) the one nearest an end
  15. 15.🔺 A current of 0.1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  16. 16.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1024 (b) 100 (c) 10 (d) 1000
  17. 17.True or false: a capacitor boosts a small signal. (a) False (b) True
  18. 18.🔺 In the V-I-R triangle, how do we find R? (a) R = V + I (b) R = V ÷ I (c) R = V × I (d) R = I ÷ V
  19. 19.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
  20. 20.🔺 A 4.8 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  21. 21.💡 What does LED stand for? (a) light-emitting diode (b) low energy device (c) light energy dial (d) large electric dial
  22. 22.🌈 A resistor has the colour bands blue, red, brown. What is its value (in ohms)?
  23. 23.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  24. 24.🔺 A current of 40 mA flows when 13.2 V is joined across a resistor. What is its resistance (in ohms)?
  25. 25.True or false: on an LED, the leg by the flat edge is the anode (+). (a) True (b) False
  26. 26.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
  27. 27.💡 Does it save or waste electricity to switch off empty rooms? (a) saves electricity (b) wastes electricity
  28. 28.⚡ A 6 W device works on 6 V. What current does it take (in amperes)? =
  29. 29.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
  30. 30.🧮 A 470 Ω resistor is joined in series with two equal 330 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  31. 31.True or false: how much a part resists is measured in amperes (A). (a) True (b) False
  32. 32.True or false: the ammeter measures voltage. (a) True (b) False
  33. 33.🔺 A 15 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  34. 34.💡 An LED is joined to a 5 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) does not light (c) lights up
  35. 35.🔺 A current of 10 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = V × R (c) I = V ÷ R (d) I = R ÷ V
  37. 37.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
  38. 38.🧮 A 3.25 V battery is joined to 5 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
  39. 39.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 2100 Ω resistor? (a) brown-red-red (b) red-brown-orange (c) red-brown-red (d) red-brown-brown
  40. 40.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)

Answer key

  1. 5
  2. 5
  3. boosts a small signal
  4. gets smaller
  5. 1.5
  6. energy used each second
  7. 1 kilowatt-hour (kWh)
  8. 0.1
  9. 255
  10. to limit the current
  11. a buzzer
  12. store charge briefly
  13. 1
  14. the one nearest an end
  15. 0.3
  16. 1000
  17. False
  18. R = V ÷ I
  19. True
  20. 40
  21. light-emitting diode
  22. 620
  23. 500
  24. 330
  25. False
  26. 900
  27. saves electricity
  28. 1
  29. ammeter
  30. 635
  31. False
  32. False
  33. 2.5
  34. may burn out
  35. 5
  36. I = V ÷ R
  37. voltmeter
  38. 0.25
  39. red-brown-red
  40. anode (+)

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