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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 931 · 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 brown, brown, red. What is its value (in ohms)?
  2. 2.🔺 A current of 3 A flows when 45 V is joined across a resistor. What is its resistance (in ohms)?
  3. 3.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to an 8 V supply. What current flows (in mA)?
  4. 4.🔺 A current of 40 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  5. 5.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  6. 6.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 25 % (c) 0 % (d) 50 %
  7. 7.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3 V supply. What current flows (in mA)?
  8. 8.🧩 Which component limits the current? (a) fuse (b) resistor (c) LDR (d) transistor
  9. 9.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 6100 Ω resistor? (a) blue-brown-orange (b) brown-blue-red (c) blue-brown-red (d) blue-brown-brown
  10. 10.⚡ A 0.9 W device works on 9 V. What current does it take (in amperes)? =
  11. 11.🔺 A 10 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  12. 12.🌈 A resistor has the colour bands white, orange, red. What is its value in kilo-ohms (kΩ)? =
  13. 13.🌈 In the resistor colour code, which number does violet stand for?
  14. 14.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 320 Ω resistor? (a) orange-red-black (b) red-orange-brown (c) orange-red-red (d) orange-red-brown
  15. 15.📏 Which unit measures the flow of charge? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
  16. 16.True or false: how much a part resists is measured in ohms (Ω). (a) True (b) False
  17. 17.📏 Which unit measures resistance? (a) ampere (A) (b) ohm (Ω) (c) watt (W) (d) volt (V)
  18. 18.📏 How many amperes (A) is 1550 mA? =
  19. 19.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
  20. 20.🧮 A 12 V battery is joined to 4 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
  21. 21.🧩 Which component senses how bright it is? (a) fuse (b) diode (c) resistor (d) LDR
  22. 22.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
  23. 23.🔍 Which is the odd one out? (a) iron one shirt at a time (b) use LED lamps (c) set the AC to 24 °C (d) switch off empty rooms
  24. 24.🔺 A 6 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
  25. 25.🔺 A current of 25 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  26. 26.📏 How many amperes (A) is 2380 mA? =
  27. 27.🌈 A resistor has the colour bands violet, blue, brown. What is its value (in ohms)?
  28. 28.💡 Why does an LED need a resistor in series? (a) to store charge (b) to limit the current (c) to make it brighter (d) to change its colour
  29. 29.🔺 A current of 10 mA flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  30. 30.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 7 hours. How many watt-hours (Wh) are saved?
  31. 31.🧮 Five equal 500 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  32. 32.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 5 V supply. What current flows (in mA)?
  33. 33.🧮 Resistors of 47 Ω and 100 Ω are joined in series. What is the total resistance (in ohms)?
  34. 34.🔺 A 6 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  35. 35.📏 In the water-pipe picture of a circuit, resistance is like … (a) a bigger tank (b) the flow of water (c) a narrow pipe (d) the water pressure
  36. 36.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) the widest gap (c) any band (d) the gold band
  37. 37.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 watt (c) 1 volt (d) 1 kilowatt-hour (kWh)
  38. 38.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it does not light (c) it lights brighter (d) it changes colour
  39. 39.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  40. 40.🔺 A current of 2.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =

Answer key

  1. 1100
  2. 15
  3. 20
  4. 12
  5. 110
  6. 5 %
  7. 10
  8. resistor
  9. blue-brown-red
  10. 0.1
  11. 2
  12. 9.3
  13. 7
  14. orange-red-brown
  15. ampere (A)
  16. True
  17. ohm (Ω)
  18. 1.55
  19. False
  20. 1
  21. LDR
  22. voltmeter
  23. iron one shirt at a time
  24. 20
  25. 8.25
  26. 2.38
  27. 760
  28. to limit the current
  29. 300
  30. 238
  31. 100
  32. 15
  33. 147
  34. 3
  35. a narrow pipe
  36. the one nearest an end
  37. 1 kilowatt-hour (kWh)
  38. it does not light
  39. cathode (−)
  40. 30

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