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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 616 · 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.💡 An LED is joined to a 6 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) does not light (c) lights up
  2. 2.Which of these is measured in ohms (Ω)? (a) the flow of charge (b) energy used each second (c) how much a part resists (d) voltage
  3. 3.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  4. 4.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) zero (c) stay the same (d) bigger
  5. 5.🧩 Which component makes things spin? (a) LDR (b) motor (c) buzzer (d) diode
  6. 6.🔺 A current of 0.25 A flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  7. 7.🔺 A current of 50 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  8. 8.🧾 A 200 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
  9. 9.⚡ A 9 W device works on 3 V. What current does it take (in amperes)? =
  10. 10.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
  11. 11.🔺 A current of 10 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  12. 12.🧾 Which lamp gives the same light for the least power? (a) an oil lamp (b) a filament bulb (c) a candle (d) an LED lamp
  13. 13.🔺 A current of 40 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.🔍 Which is the odd one out? (a) use LED lamps (b) use daylight to read (c) leave fridge door open (d) switch off empty rooms
  15. 15.🔺 A 12 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  16. 16.🔺 A 9 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  17. 17.🌈 A resistor has the colour bands white, red, orange. What is its value (in ohms)?
  18. 18.🧩 A capacitor in a circuit can … (a) store charge briefly (b) spin a wheel (c) measure heat (d) make light
  19. 19.🌈 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
  20. 20.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 50 % (c) 25 % (d) 0 %
  21. 21.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
  22. 22.Which of these is measured in volts (V)? (a) the flow of charge (b) how much a part resists (c) energy used each second (d) the push of a cell
  23. 23.🧮 Resistors of 50 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
  24. 24.💡 Does it save or waste electricity to run fans in empty rooms? (a) saves electricity (b) wastes electricity
  25. 25.📏 Which unit measures current? (a) watt (W) (b) ampere (A) (c) ohm (Ω) (d) volt (V)
  26. 26.⚡ A device works on 12 V and takes 0.2 A. What is its power (in watts)? =
  27. 27.🌈 In the resistor colour code, which number does violet stand for?
  28. 28.🔺 A current of 20 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  29. 29.🔺 A 20 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  30. 30.Which of these is measured in watts (W)? (a) how much a part resists (b) current (c) power (d) resistance
  31. 31.🔺 In the V-I-R triangle, how do we find V? (a) V = I × R (b) V = I ÷ R (c) V = R ÷ I (d) V = I + R
  32. 32.🧮 Five equal 250 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  33. 33.🧮 A 0.7 V battery is joined to 5 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
  34. 34.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = I ÷ V (c) P = V × I (d) P = V + I
  35. 35.🔺 A current of 2.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 9000 Ω resistor? (a) brown-white-red (b) white-black-brown (c) white-black-red (d) white-black-orange
  37. 37.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
  38. 38.True or false: the ammeter is joined across a part. (a) True (b) False
  39. 39.🧩 Which component has coloured bands? (a) resistor (b) motor (c) fuse (d) buzzer
  40. 40.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?

Answer key

  1. does not light
  2. how much a part resists
  3. 1
  4. bigger
  5. motor
  6. 20
  7. 15
  8. 0.8
  9. 3
  10. True
  11. 2.5
  12. an LED lamp
  13. 20
  14. leave fridge door open
  15. 3
  16. 3
  17. 92000
  18. store charge briefly
  19. the one nearest an end
  20. 5 %
  21. True
  22. the push of a cell
  23. 97
  24. wastes electricity
  25. ampere (A)
  26. 2.4
  27. 7
  28. 9.4
  29. 50
  30. power
  31. V = I × R
  32. 50
  33. 0.1
  34. P = V × I
  35. 7.5
  36. white-black-red
  37. ammeter
  38. False
  39. resistor
  40. 2300

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