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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 150 · 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.True or false: how much a part resists is measured in amperes (A). (a) True (b) False
  2. 2.⚡ A device works on 3 V and takes 0.1 A. What is its power (in watts)? =
  3. 3.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  4. 4.🧩 A capacitor in a circuit can … (a) spin a wheel (b) measure heat (c) store charge briefly (d) make light
  5. 5.True or false: to use daylight to read wastes electricity. (a) True (b) False
  6. 6.🌈 Which band is read first on a resistor? (a) the widest gap (b) the gold band (c) any band (d) the one nearest an end
  7. 7.🌈 A resistor has the colour bands grey, violet, orange. What is its value (in ohms)?
  8. 8.🔺 A current of 0.25 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  9. 9.🔺 A current of 0.1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  10. 10.🔺 A current of 10 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  11. 11.🔺 A 12 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  12. 12.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 5 hours. How many watt-hours (Wh) are saved?
  13. 13.💡 A red LED uses 2 V and should get 20 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
  14. 14.🧮 Resistors of 47 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
  15. 15.Which of these is measured in watts (W)? (a) voltage (b) energy used each second (c) current (d) the flow of charge
  16. 16.📏 How many amperes (A) is 190 mA? =
  17. 17.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) bigger (c) stay the same (d) zero
  18. 18.🔺 A current of 50 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  19. 19.💡 Does it save or waste electricity to close the fridge quickly? (a) saves electricity (b) wastes electricity
  20. 20.True or false: resistance is measured in watts (W). (a) False (b) True
  21. 21.💡 Does it save or waste electricity to unplug idle chargers? (a) wastes electricity (b) saves electricity
  22. 22.🧮 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
  23. 23.🔺 A current of 2 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  24. 24.🔺 A 2.4 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  25. 25.True or false: the ammeter measures voltage. (a) False (b) True
  26. 26.📏 Which unit measures the push of a cell? (a) ohm (Ω) (b) watt (W) (c) ampere (A) (d) volt (V)
  27. 27.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 78000 Ω resistor? (a) violet-grey-orange (b) grey-violet-orange (c) violet-grey-red (d) violet-grey-yellow
  28. 28.💡 Does it save or waste electricity to switch off empty rooms? (a) saves electricity (b) wastes electricity
  29. 29.🧮 Three equal 15 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  30. 30.🔺 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
  31. 31.🧩 Which component limits the current? (a) potentiometer (b) capacitor (c) thermistor (d) resistor
  32. 32.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 11 Ω resistor? (a) brown-brown-brown (b) brown-brown-black (c) red-brown-black (d) brown-red-black
  33. 33.🔺 A current of 0.5 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  34. 34.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  35. 35.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
  36. 36.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  37. 37.🧩 Which component has coloured bands? (a) resistor (b) buzzer (c) motor (d) LED
  38. 38.True or false: the voltmeter measures voltage. (a) False (b) True
  39. 39.📏 How many amperes (A) is 1400 mA? =
  40. 40.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1024 (b) 1000 (c) 100 (d) 10

Answer key

  1. False
  2. 0.3
  3. 10
  4. store charge briefly
  5. False
  6. the one nearest an end
  7. 87000
  8. 1
  9. 1.2
  10. 500
  11. 1.5
  12. 255
  13. 200
  14. 57
  15. energy used each second
  16. 0.19
  17. bigger
  18. 7.5
  19. saves electricity
  20. False
  21. saves electricity
  22. less than either one
  23. 12
  24. 20
  25. False
  26. volt (V)
  27. violet-grey-orange
  28. saves electricity
  29. 5
  30. I = V ÷ R
  31. resistor
  32. brown-brown-black
  33. 7.5
  34. 500
  35. 230
  36. cathode (−)
  37. resistor
  38. True
  39. 1.4
  40. 1000

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