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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 725 · 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 40 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  2. 2.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V + R (c) I = V × R (d) I = V ÷ R
  3. 3.🔺 A current of 0.25 A flows when 0.75 V is joined across a resistor. What is its resistance (in ohms)?
  4. 4.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 4 V supply. What current flows (in mA)?
  5. 5.🔺 A current of 20 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  6. 6.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 7800 Ω resistor? (a) violet-grey-red (b) grey-violet-red (c) violet-grey-orange (d) violet-grey-brown
  7. 7.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 kilowatt-hour (kWh) (c) 1 ampere (d) 1 watt
  8. 8.🔺 A current of 1.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  9. 9.True or false: to iron one shirt at a time saves electricity. (a) True (b) False
  10. 10.🌈 In the resistor colour code, which number does orange stand for?
  11. 11.🔺 A current of 50 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  12. 12.🔺 A current of 20 mA flows when 6.6 V is joined across a resistor. What is its resistance (in ohms)?
  13. 13.True or false: the push of a cell is measured in volts (V). (a) True (b) False
  14. 14.True or false: on an LED, the longer leg is the anode (+). (a) False (b) True
  15. 15.🔺 A 2 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  16. 16.🧮 Four equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  17. 17.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
  18. 18.💡 What does LED stand for? (a) low energy device (b) large electric dial (c) light-emitting diode (d) light energy dial
  19. 19.🔺 A current of 10 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.🔍 Which is the odd one out? (a) use old filament bulbs (b) switch off empty rooms (c) use daylight to read (d) set the AC to 24 °C
  21. 21.⚡ A device works on 12 V and takes 0.25 A. What is its power (in watts)? =
  22. 22.🔍 Which is the odd one out? (a) leave the TV on standby (b) leave fridge door open (c) run fans in empty rooms (d) set the AC to 24 °C
  23. 23.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
  24. 24.What does a capacitor do? (a) limits the current (b) has coloured bands (c) is a resistance knob (d) stores a little charge
  25. 25.True or false: a diode stores a little charge. (a) True (b) False
  26. 26.🌈 A resistor has the colour bands grey, violet, yellow. What is its value in kilo-ohms (kΩ)? =
  27. 27.🔍 Which is the odd one out? (a) use LED lamps (b) iron one shirt at a time (c) use old filament bulbs (d) leave fridge door open
  28. 28.⚡ A 72 W device works on 24 V. What current does it take (in amperes)? =
  29. 29.🔺 A current of 2.5 A flows when 37.5 V is joined across a resistor. What is its resistance (in ohms)?
  30. 30.🔺 A current of 20 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.🧩 Which component has coloured bands? (a) diode (b) transistor (c) LDR (d) resistor
  32. 32.🧮 Resistors of 33 Ω, 50 Ω, 68 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
  33. 33.🔺 A current of 2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  34. 34.🌈 In the resistor colour code, which number does grey stand for?
  35. 35.🔺 A current of 20 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 1100 Ω resistor? (a) brown-brown-orange (b) brown-brown-red (c) brown-brown-brown (d) brown-red-red
  37. 37.🌈 A resistor has the colour bands violet, red, yellow. What is its value in kilo-ohms (kΩ)? =
  38. 38.💡 An LED is joined to a 3 V battery through a 1000 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) does not light (b) lights up (c) may burn out
  39. 39.📏 Which unit measures power? (a) ampere (A) (b) watt (W) (c) volt (V) (d) ohm (Ω)
  40. 40.True or false: a potentiometer has coloured bands. (a) True (b) False

Answer key

  1. 13.2
  2. I = V ÷ R
  3. 3
  4. 10
  5. 500
  6. violet-grey-red
  7. 1 kilowatt-hour (kWh)
  8. 18
  9. False
  10. 3
  11. 11
  12. 330
  13. True
  14. True
  15. 0.1
  16. 25
  17. 230
  18. light-emitting diode
  19. 3.3
  20. use old filament bulbs
  21. 3
  22. set the AC to 24 °C
  23. voltmeter
  24. stores a little charge
  25. False
  26. 870
  27. use LED lamps
  28. 3
  29. 15
  30. 6
  31. resistor
  32. 301
  33. 8
  34. 8
  35. 10
  36. brown-brown-red
  37. 720
  38. lights up
  39. watt (W)
  40. False

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