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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 583 · 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 50 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  2. 2.🌈 Which band is read first on a resistor? (a) the gold band (b) the one nearest an end (c) the widest gap (d) any band
  3. 3.💡 A red LED uses 2 V and should get 10 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  4. 4.🔺 A current of 2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  5. 5.🔺 A current of 2.5 A flows when 15 V is joined across a resistor. What is its resistance (in ohms)?
  6. 6.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
  7. 7.💡 Does it save or waste electricity to leave the TV on standby? (a) saves electricity (b) wastes electricity
  8. 8.🔺 An 18.8 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  9. 9.📏 How many milliamperes (mA) is 1.49 A?
  10. 10.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 2 hours. How many watt-hours (Wh) are saved?
  11. 11.🌈 A resistor has the colour bands red, blue, red. What is its value (in ohms)?
  12. 12.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 96000 Ω resistor? (a) white-blue-red (b) white-blue-yellow (c) blue-white-orange (d) white-blue-orange
  13. 13.True or false: the push of a cell is measured in volts (V). (a) False (b) True
  14. 14.True or false: to use daylight to read wastes electricity. (a) False (b) True
  15. 15.True or false: the push of a cell is measured in watts (W). (a) True (b) False
  16. 16.🔺 A current of 0.1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.💡 An LED is joined to a 5 V battery through a 470 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) lights up (c) does not light
  18. 18.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 3 V supply. What current flows (in mA)?
  19. 19.True or false: a capacitor makes things spin. (a) True (b) False
  20. 20.🧮 A 10 Ω resistor is joined in series with two equal 40 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  21. 21.🌈 In the resistor colour code, which number does violet stand for?
  22. 22.🧮 A 3.2 V battery is joined to 8 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
  23. 23.🔍 Which is the odd one out? (a) leave the TV on standby (b) set the AC to 24 °C (c) iron one shirt at a time (d) run fans in empty rooms
  24. 24.What does a motor do? (a) stores a little charge (b) is a resistance knob (c) turns a fan or wheels (d) limits the current
  25. 25.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 98000 Ω resistor? (a) white-grey-orange (b) grey-white-orange (c) white-grey-yellow (d) white-grey-red
  26. 26.🧮 Five equal 125 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  27. 27.🔺 A current of 0.1 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  28. 28.🔍 Which is the odd one out? (a) set the AC to 24 °C (b) switch off empty rooms (c) use LED lamps (d) leave fridge door open
  29. 29.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = I ÷ V (d) P = V × I
  30. 30.🔺 A current of 40 mA flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  31. 31.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 0 % (c) 25 % (d) 50 %
  32. 32.True or false: a thermistor senses how hot it is. (a) False (b) True
  33. 33.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) smaller (c) zero (d) bigger
  34. 34.🧮 Resistors of 100 Ω, 150 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
  35. 35.🔺 A 0.75 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  36. 36.Which of these is measured in volts (V)? (a) current (b) power (c) voltage (d) how much a part resists
  37. 37.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 kilowatt-hour (kWh) (c) 1 ampere (d) 1 volt
  38. 38.Which of these is measured in ohms (Ω)? (a) power (b) voltage (c) how much a part resists (d) the flow of charge
  39. 39.🔺 A current of 10 mA flows when 2.2 V is joined across a resistor. What is its resistance (in ohms)?
  40. 40.🧮 Resistors of 68 Ω, 20 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?

Answer key

  1. 12.5
  2. the one nearest an end
  3. 300
  4. 8
  5. 6
  6. voltmeter
  7. wastes electricity
  8. 40
  9. 1490
  10. 170
  11. 2600
  12. white-blue-orange
  13. True
  14. False
  15. False
  16. 0.2
  17. lights up
  18. 5
  19. False
  20. 30
  21. 7
  22. 0.2
  23. set the AC to 24 °C
  24. turns a fan or wheels
  25. white-grey-orange
  26. 25
  27. 1.5
  28. leave fridge door open
  29. P = V × I
  30. 150
  31. 5 %
  32. True
  33. bigger
  34. 300
  35. 0.25
  36. voltage
  37. 1 kilowatt-hour (kWh)
  38. how much a part resists
  39. 220
  40. 418

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