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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 943 · 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.🧩 Which component limits the current? (a) LED (b) resistor (c) LDR (d) capacitor
  2. 2.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V × I (c) P = V + I (d) P = I ÷ V
  3. 3.📏 Which unit measures the flow of charge? (a) ampere (A) (b) ohm (Ω) (c) watt (W) (d) volt (V)
  4. 4.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
  5. 5.True or false: a resistor has coloured bands. (a) True (b) False
  6. 6.🔺 A current of 1 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  7. 7.🔺 A current of 25 mA flows when 6.25 V is joined across a resistor. What is its resistance (in ohms)?
  8. 8.📏 Which unit measures the push of a cell? (a) watt (W) (b) ohm (Ω) (c) volt (V) (d) ampere (A)
  9. 9.🧾 One “unit” on an electricity bill is … (a) 1 kilowatt-hour (kWh) (b) 1 ampere (c) 1 watt (d) 1 volt
  10. 10.🧮 A 100 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)?
  11. 11.🔺 A current of 0.2 A flows when 0.4 V is joined across a resistor. What is its resistance (in ohms)?
  12. 12.🧮 A 470 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)?
  13. 13.🔺 A 2.5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
  14. 14.🔺 A 2 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  15. 15.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
  16. 16.True or false: a buzzer makes a beeping sound. (a) True (b) False
  17. 17.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V ÷ I (c) R = V + I (d) R = V × I
  18. 18.⚡ A 0.3 W device works on 1.5 V. What current does it take (in amperes)? =
  19. 19.💡 An LED is joined to a 3 V battery through a 1000 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
  20. 20.What does an LDR do? (a) senses how bright it is (b) is a resistance knob (c) blows if current is high (d) has coloured bands
  21. 21.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
  22. 22.🔺 A current of 20 mA flows when 9.4 V is joined across a resistor. What is its resistance (in ohms)?
  23. 23.🧮 Resistors of 330 Ω, 20 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
  24. 24.🔺 A current of 1 A flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  25. 25.🧾 Which lamp gives the same light for the least power? (a) a candle (b) an LED lamp (c) a filament bulb (d) an oil lamp
  26. 26.🔺 A current of 50 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  27. 27.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  28. 28.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  29. 29.🌈 Which band is read first on a resistor? (a) the widest gap (b) any band (c) the one nearest an end (d) the gold band
  30. 30.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
  31. 31.🧮 A 150 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  32. 32.🔺 A 7.5 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  33. 33.⚡ Power tells us … (a) the size of a cell (b) energy used each second (c) the colour of light (d) the length of a wire
  34. 34.Which of these wastes electricity? (a) use LED lamps (b) set the AC to 24 °C (c) unplug idle chargers (d) leave the TV on standby
  35. 35.🧮 A 47 Ω resistor is joined in series with two equal 470 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  36. 36.🔺 A current of 20 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  37. 37.True or false: a resistor limits the current. (a) False (b) True
  38. 38.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 4000 Ω resistor? (a) green-yellow-red (b) yellow-black-red (c) yellow-black-orange (d) yellow-black-brown
  39. 39.🔍 Which is the odd one out? (a) close the fridge quickly (b) switch off empty rooms (c) use old filament bulbs (d) set the AC to 24 °C
  40. 40.🧩 Which component is a resistance knob? (a) potentiometer (b) thermistor (c) resistor (d) buzzer

Answer key

  1. resistor
  2. P = V × I
  3. ampere (A)
  4. 460
  5. True
  6. 8
  7. 250
  8. volt (V)
  9. 1 kilowatt-hour (kWh)
  10. 265
  11. 2
  12. 635
  13. 10
  14. 0.5
  15. voltmeter
  16. True
  17. R = V ÷ I
  18. 0.2
  19. lights up
  20. senses how bright it is
  21. 920
  22. 470
  23. 360
  24. 5
  25. an LED lamp
  26. 100
  27. cathode (−)
  28. 345
  29. the one nearest an end
  30. voltmeter
  31. 155
  32. 1.5
  33. energy used each second
  34. leave the TV on standby
  35. 282
  36. 8
  37. True
  38. yellow-black-red
  39. use old filament bulbs
  40. potentiometer

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