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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 676 · 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 25 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  2. 2.🧮 Five equal 125 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  3. 3.Which of these is measured in volts (V)? (a) current (b) resistance (c) the flow of charge (d) voltage
  4. 4.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) stays the same (c) gets smaller (d) gets bigger
  5. 5.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) stay the same (c) bigger (d) smaller
  6. 6.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 25 % (c) 50 % (d) 0 %
  7. 7.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  8. 8.🧮 A 68 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)?
  9. 9.🔺 A 16.5 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
  10. 10.🔺 A current of 25 mA flows when 8.25 V is joined across a resistor. What is its resistance (in ohms)?
  11. 11.📏 How many ohms (Ω) is 1.6 kΩ?
  12. 12.🌈 In the resistor colour code, which number does red stand for?
  13. 13.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  14. 14.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 100 (b) 10 (c) 1024 (d) 1000
  15. 15.🔺 A current of 25 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  16. 16.🔺 A current of 20 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.🔺 A current of 3 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  18. 18.True or false: the flow of charge is measured in amperes (A). (a) True (b) False
  19. 19.📏 Which unit measures energy used each second? (a) ohm (Ω) (b) watt (W) (c) ampere (A) (d) volt (V)
  20. 20.🔺 A 5 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  21. 21.🌈 Which band is read first on a resistor? (a) any band (b) the widest gap (c) the one nearest an end (d) the gold band
  22. 22.📏 How many amperes (A) is 610 mA? =
  23. 23.🔺 A 5 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  24. 24.📏 How many milliamperes (mA) make 1 ampere? (a) 100 (b) 1000 (c) 60 (d) 10
  25. 25.🔺 A current of 20 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  26. 26.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
  27. 27.🧩 Which component blows if current is high? (a) potentiometer (b) fuse (c) diode (d) thermistor
  28. 28.🔺 A current of 0.25 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  29. 29.🔺 A current of 10 mA flows when 4.7 V is joined across a resistor. What is its resistance (in ohms)?
  30. 30.🔺 A current of 10 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.🔺 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
  32. 32.True or false: the ammeter is joined in series. (a) False (b) True
  33. 33.🌈 A resistor has the colour bands orange, violet, brown. What is its value (in ohms)?
  34. 34.🔺 A current of 10 mA flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
  35. 35.🔺 A 1 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  36. 36.🧾 A 1500 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
  37. 37.💡 An LED is joined to a 3 V battery through a 470 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) lights up (c) may burn out
  38. 38.True or false: the ammeter measures current. (a) False (b) True
  39. 39.🔍 Which is the odd one out? (a) unplug idle chargers (b) leave fridge door open (c) close the fridge quickly (d) switch off empty rooms
  40. 40.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) a candle (c) an oil lamp (d) an LED lamp

Answer key

  1. 50
  2. 25
  3. voltage
  4. gets smaller
  5. bigger
  6. 5 %
  7. 345
  8. 233
  9. 50
  10. 330
  11. 1600
  12. 2
  13. cathode (−)
  14. 1000
  15. 3.75
  16. 4
  17. 45
  18. True
  19. watt (W)
  20. 1
  21. the one nearest an end
  22. 0.61
  23. 2.5
  24. 1000
  25. 6
  26. voltmeter
  27. fuse
  28. 2.5
  29. 470
  30. 4
  31. I = V ÷ R
  32. True
  33. 370
  34. 250
  35. 0.5
  36. 15
  37. lights up
  38. True
  39. leave fridge door open
  40. an LED lamp

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