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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 483 · 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 capacitor in a circuit can … (a) store charge briefly (b) spin a wheel (c) measure heat (d) make light
  2. 2.🧮 Five equal 25 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  3. 3.What does a thermistor do? (a) stores a little charge (b) turns a fan or wheels (c) beeps for an alarm (d) senses how hot it is
  4. 4.What does a transistor do? (a) smooths a wobbly supply (b) turns a fan or wheels (c) boosts a small signal (d) glows using little power
  5. 5.📏 How many amperes (A) is 1440 mA? =
  6. 6.🌈 In the resistor colour code, which number does red stand for?
  7. 7.🧮 Resistors of 68 Ω, 150 Ω, 150 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
  8. 8.💡 Does it save or waste electricity to set the AC to 24 °C? (a) wastes electricity (b) saves electricity
  9. 9.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
  10. 10.⚡ A 13.5 W device works on 9 V. What current does it take (in amperes)? =
  11. 11.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it makes a sound (c) it lights brighter (d) it does not light
  12. 12.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  13. 13.What does a capacitor do? (a) limits the current (b) blows if current is high (c) glows using little power (d) smooths a wobbly supply
  14. 14.True or false: the ammeter measures voltage. (a) False (b) True
  15. 15.🔺 A 60 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  16. 16.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) stay the same (c) smaller (d) bigger
  17. 17.⚡ Power tells us … (a) the size of a cell (b) the length of a wire (c) the colour of light (d) energy used each second
  18. 18.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = I × R (c) V = I ÷ R (d) V = R ÷ I
  19. 19.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
  20. 20.🔺 A current of 3 A flows when 9 V is joined across a resistor. What is its resistance (in ohms)?
  21. 21.🔺 A current of 3 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  22. 22.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
  23. 23.🔺 A current of 0.25 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  24. 24.🔺 A 4 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  25. 25.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 0 % (c) 50 % (d) 25 %
  26. 26.🔺 A current of 10 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  27. 27.💡 Does it save or waste electricity to close the fridge quickly? (a) saves electricity (b) wastes electricity
  28. 28.🔺 A current of 50 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  29. 29.🔺 A current of 3 A flows when 15 V is joined across a resistor. What is its resistance (in ohms)?
  30. 30.Which of these saves electricity? (a) set the AC to 24 °C (b) leave fridge door open (c) use old filament bulbs (d) leave the TV on standby
  31. 31.🔺 A 1.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  32. 32.🧮 A 2.2 V battery is joined to 5 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
  33. 33.⚡ A device works on 24 V and takes 0.5 A. What is its power (in watts)? =
  34. 34.📏 How many kilo-ohms (kΩ) is 4000 Ω? =
  35. 35.🔍 Which is the odd one out? (a) leave fridge door open (b) use LED lamps (c) leave the TV on standby (d) use old filament bulbs
  36. 36.🔺 A current of 0.25 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  37. 37.🔍 Which is the odd one out? (a) leave fridge door open (b) switch off empty rooms (c) set the AC to 24 °C (d) close the fridge quickly
  38. 38.🔺 A current of 0.1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  39. 39.🌈 A resistor has the colour bands brown, yellow, orange. What is its value in kilo-ohms (kΩ)? =
  40. 40.🔺 A current of 2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =

Answer key

  1. store charge briefly
  2. 5
  3. senses how hot it is
  4. boosts a small signal
  5. 1.44
  6. 2
  7. 418
  8. saves electricity
  9. ammeter
  10. 1.5
  11. it does not light
  12. 1
  13. smooths a wobbly supply
  14. False
  15. 3
  16. bigger
  17. energy used each second
  18. V = I × R
  19. voltmeter
  20. 3
  21. 12
  22. 1150
  23. 1
  24. 40
  25. 5 %
  26. 4
  27. saves electricity
  28. 6
  29. 5
  30. set the AC to 24 °C
  31. 10
  32. 0.2
  33. 12
  34. 4
  35. use LED lamps
  36. 2.5
  37. leave fridge door open
  38. 0.2
  39. 14
  40. 6

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