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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 675 · 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 current of 20 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  2. 2.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 25 % (c) 5 % (d) 50 %
  3. 3.🧮 Five equal 500 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  4. 4.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = R ÷ I (c) V = I × R (d) V = I + R
  5. 5.🔺 A current of 1.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.Which of these saves electricity? (a) run fans in empty rooms (b) iron one shirt at a time (c) leave the TV on standby (d) unplug idle chargers
  7. 7.🧾 One “unit” on an electricity bill is … (a) 1 kilowatt-hour (kWh) (b) 1 volt (c) 1 watt (d) 1 ampere
  8. 8.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
  9. 9.🌈 A resistor has the colour bands blue, green, orange. What is its value (in ohms)?
  10. 10.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) stays the same (c) gets smaller (d) becomes zero
  11. 11.🌈 In the resistor colour code, which number does black stand for?
  12. 12.🔺 A 12 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  13. 13.🧩 A capacitor in a circuit can … (a) make light (b) measure heat (c) spin a wheel (d) store charge briefly
  14. 14.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  15. 15.True or false: a transistor boosts a small signal. (a) False (b) True
  16. 16.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V ÷ I (c) R = V + I (d) R = V × I
  17. 17.🔺 A current of 50 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  18. 18.🌈 A resistor has the colour bands red, brown, black. What is its value (in ohms)?
  19. 19.🧮 Three equal 300 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  20. 20.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 6700 Ω resistor? (a) blue-violet-brown (b) blue-violet-red (c) violet-blue-red (d) blue-violet-orange
  21. 21.💡 Does it save or waste electricity to use daylight to read? (a) wastes electricity (b) saves electricity
  22. 22.🌈 In the resistor colour code, which number does white stand for?
  23. 23.⚡ A device works on 5 V and takes 1 A. What is its power (in watts)? =
  24. 24.🧾 A 200 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
  25. 25.⚡ A device works on 12 V and takes 1.5 A. What is its power (in watts)? =
  26. 26.🧮 Four equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  27. 27.🧮 Five equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  28. 28.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) zero (c) stay the same (d) smaller
  29. 29.💡 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?
  30. 30.📏 How many kilo-ohms (kΩ) is 10000 Ω? =
  31. 31.📏 Which unit measures how much a part resists? (a) watt (W) (b) ampere (A) (c) ohm (Ω) (d) volt (V)
  32. 32.💡 An LED is joined to a 6 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) may burn out (c) lights up
  33. 33.🌈 A resistor has the colour bands blue, yellow, orange. What is its value (in ohms)?
  34. 34.True or false: the ammeter is joined in series. (a) False (b) True
  35. 35.🔺 A current of 0.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.⚡ A device works on 9 V and takes 0.1 A. What is its power (in watts)? =
  37. 37.🌈 A resistor has the colour bands white, white, orange. What is its value in kilo-ohms (kΩ)? =
  38. 38.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to an 8 V supply. What current flows (in mA)?
  39. 39.🧮 A 68 Ω resistor is joined in series with two equal 50 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  40. 40.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?

Answer key

  1. 10
  2. 5 %
  3. 100
  4. V = I × R
  5. 9
  6. unplug idle chargers
  7. 1 kilowatt-hour (kWh)
  8. True
  9. 65000
  10. gets smaller
  11. 0
  12. 1
  13. store charge briefly
  14. 25
  15. True
  16. R = V ÷ I
  17. 20
  18. 21
  19. 100
  20. blue-violet-red
  21. saves electricity
  22. 9
  23. 5
  24. 1.2
  25. 18
  26. 5
  27. 20
  28. bigger
  29. 900
  30. 10
  31. ohm (Ω)
  32. may burn out
  33. 64000
  34. True
  35. 2
  36. 0.9
  37. 99
  38. 20
  39. 93
  40. 235

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