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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 146 · 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.

NameDateTime takenScore ___ / 40
  1. 1.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
  2. 2.⚡ A 13.5 W device works on 9 V. What current does it take (in amperes)? =
  3. 3.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets bigger (c) stays the same (d) gets smaller
  4. 4.🔺 A current of 40 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  5. 5.🔺 A current of 20 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.🔺 A current of 40 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  7. 7.🔺 A current of 3 A flows when 24 V is joined across a resistor. What is its resistance (in ohms)?
  8. 8.💡 What does LED stand for? (a) low energy device (b) light energy dial (c) light-emitting diode (d) large electric dial
  9. 9.📏 Which unit measures current? (a) ampere (A) (b) volt (V) (c) watt (W) (d) ohm (Ω)
  10. 10.🔺 A current of 10 mA flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  11. 11.⚡ A 48 W device works on 24 V. What current does it take (in amperes)? =
  12. 12.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
  13. 13.🔺 A current of 10 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.⚡ Power tells us … (a) the length of a wire (b) energy used each second (c) the size of a cell (d) the colour of light
  15. 15.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) bigger (c) stay the same (d) zero
  16. 16.💡 An LED is joined to a 6 V battery through a 1000 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) lights up (c) does not light
  17. 17.True or false: the voltmeter measures current. (a) True (b) False
  18. 18.💡 Does it save or waste electricity to iron one shirt at a time? (a) saves electricity (b) wastes electricity
  19. 19.🧾 A 2000 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
  20. 20.Which of these saves electricity? (a) use old filament bulbs (b) iron one shirt at a time (c) run fans in empty rooms (d) unplug idle chargers
  21. 21.🧩 A capacitor in a circuit can … (a) spin a wheel (b) make light (c) measure heat (d) store charge briefly
  22. 22.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
  23. 23.🧮 Resistors of 33 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
  24. 24.True or false: a diode stores a little charge. (a) False (b) True
  25. 25.🧩 Which component lets current go one way? (a) LDR (b) diode (c) resistor (d) thermistor
  26. 26.🌈 In the resistor colour code, which number does yellow stand for?
  27. 27.🔺 A 15 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  28. 28.🧮 A 1.6 V battery is joined to 3 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
  29. 29.🌈 A resistor has the colour bands red, violet, orange. What is its value in kilo-ohms (kΩ)? =
  30. 30.🔺 A 37.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  31. 31.Which of these saves electricity? (a) use LED lamps (b) run fans in empty rooms (c) leave fridge door open (d) use old filament bulbs
  32. 32.🔺 A current of 2.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  33. 33.🧮 A 1.4 V battery is joined to 3 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
  34. 34.🌈 A resistor has the colour bands white, brown, orange. What is its value in kilo-ohms (kΩ)? =
  35. 35.True or false: a buzzer makes a beeping sound. (a) False (b) True
  36. 36.📏 How many amperes (A) is 2500 mA? =
  37. 37.🌈 A resistor has the colour bands yellow, red, red. What is its value in kilo-ohms (kΩ)? =
  38. 38.🔺 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
  39. 39.Which of these saves electricity? (a) iron one shirt at a time (b) leave the TV on standby (c) use old filament bulbs (d) switch off empty rooms
  40. 40.🧩 Which component smooths a wobbly supply? (a) LDR (b) capacitor (c) buzzer (d) thermistor

Answer key

  1. False
  2. 1.5
  3. gets smaller
  4. 4
  5. 8
  6. 4.8
  7. 8
  8. light-emitting diode
  9. ampere (A)
  10. 300
  11. 2
  12. 600
  13. 3
  14. energy used each second
  15. bigger
  16. lights up
  17. False
  18. wastes electricity
  19. 8
  20. unplug idle chargers
  21. store charge briefly
  22. 1840
  23. 43
  24. False
  25. diode
  26. 4
  27. 2.5
  28. 0.2
  29. 27
  30. 2.5
  31. use LED lamps
  32. 12.5
  33. 0.2
  34. 91
  35. True
  36. 2.5
  37. 4.2
  38. I = V ÷ R
  39. switch off empty rooms
  40. capacitor

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