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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 423 · 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 resistor has the colour bands yellow, green, black. What is its value (in ohms)?
  2. 2.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 5 % (d) 25 %
  3. 3.🌈 A resistor has the colour bands orange, orange, red. What is its value in kilo-ohms (kΩ)? =
  4. 4.True or false: on an LED, the round-side leg is the anode (+). (a) True (b) False
  5. 5.📏 Which unit measures current? (a) ampere (A) (b) watt (W) (c) volt (V) (d) ohm (Ω)
  6. 6.🔺 A current of 0.5 A flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
  7. 7.🔺 A current of 20 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  8. 8.🔺 A current of 50 mA flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  9. 9.True or false: on an LED, the shorter leg is the anode (+). (a) True (b) False
  10. 10.📏 How many milliamperes (mA) is 0.68 A?
  11. 11.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1000 (b) 1024 (c) 10 (d) 100
  12. 12.Which of these is measured in volts (V)? (a) voltage (b) the flow of charge (c) power (d) how much a part resists
  13. 13.⚡ A 1.5 W device works on 3 V. What current does it take (in amperes)? =
  14. 14.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to store charge (c) to limit the current (d) to change its colour
  15. 15.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) stays the same (c) becomes zero (d) gets smaller
  16. 16.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 5400 Ω resistor? (a) green-yellow-orange (b) green-yellow-brown (c) yellow-green-red (d) green-yellow-red
  17. 17.🔺 A current of 1.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  18. 18.📏 How many kilowatts (kW) is 4600 W? =
  19. 19.🔺 In the V-I-R triangle, how do we find V? (a) V = I × R (b) V = I + R (c) V = R ÷ I (d) V = I ÷ R
  20. 20.🧩 Which part changes electrical energy into movement? (a) a motor (b) a fuse (c) an LED (d) a resistor
  21. 21.⚡ A device works on 12 V and takes 3 A. What is its power (in watts)? =
  22. 22.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = I ÷ V (d) P = V × I
  24. 24.🔺 A current of 1.5 A flows when 18 V is joined across a resistor. What is its resistance (in ohms)?
  25. 25.🔺 A current of 10 mA flows when 4.7 V is joined across a resistor. What is its resistance (in ohms)?
  26. 26.🧮 A 4.5 V battery is joined to 4 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
  27. 27.🔺 A current of 25 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  28. 28.📏 How many watts (W) is 1.2 kW?
  29. 29.Which of these wastes electricity? (a) use daylight to read (b) iron one shirt at a time (c) set the AC to 24 °C (d) switch off empty rooms
  30. 30.🔺 A current of 40 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.What does a transistor do? (a) senses how bright it is (b) makes a beeping sound (c) smooths a wobbly supply (d) boosts a small signal
  32. 32.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  33. 33.💡 What happens if an LED is put in backwards? (a) it does not light (b) it makes a sound (c) it lights brighter (d) it changes colour
  34. 34.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V ÷ R (c) I = R ÷ V (d) I = V + R
  35. 35.🌈 In the resistor colour code, which number does green stand for?
  36. 36.🧮 Three equal 300 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  37. 37.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  38. 38.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 2.75 V supply. What current flows (in mA)?
  39. 39.🔺 A current of 50 mA flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
  40. 40.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) zero (c) stay the same (d) smaller

Answer key

  1. 45
  2. 5 %
  3. 3.3
  4. True
  5. ampere (A)
  6. 15
  7. 100
  8. 120
  9. False
  10. 680
  11. 1000
  12. voltage
  13. 0.5
  14. to limit the current
  15. gets smaller
  16. green-yellow-red
  17. 15
  18. 4.6
  19. V = I × R
  20. a motor
  21. 36
  22. 1.2
  23. P = V × I
  24. 12
  25. 470
  26. 0.5
  27. 2.5
  28. 1200
  29. iron one shirt at a time
  30. 20
  31. boosts a small signal
  32. cathode (−)
  33. it does not light
  34. I = V ÷ R
  35. 5
  36. 100
  37. anode (+)
  38. 5
  39. 400
  40. bigger

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