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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 686 · 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 3 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  2. 2.🌈 Which band is read first on a resistor? (a) any band (b) the widest gap (c) the one nearest an end (d) the gold band
  3. 3.True or false: the voltmeter is joined across a part. (a) False (b) True
  4. 4.🔺 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
  5. 5.💡 What does LED stand for? (a) light energy dial (b) light-emitting diode (c) large electric dial (d) low energy device
  6. 6.🌈 A resistor has the colour bands yellow, yellow, red. What is its value (in ohms)?
  7. 7.🧩 A capacitor in a circuit can … (a) measure heat (b) store charge briefly (c) make light (d) spin a wheel
  8. 8.🌈 A resistor has the colour bands white, white, red. What is its value in kilo-ohms (kΩ)? =
  9. 9.🔺 A current of 2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  10. 10.🌈 A resistor has the colour bands brown, black, red. What is its value in kilo-ohms (kΩ)? =
  11. 11.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 4 V supply. What current flows (in mA)?
  12. 12.🔺 A current of 40 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  13. 13.🧮 Resistors of 20 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
  14. 14.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  15. 15.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) stays the same (c) gets smaller (d) becomes zero
  16. 16.🌈 A resistor has the colour bands red, white, brown. What is its value (in ohms)?
  17. 17.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) bigger (c) smaller (d) stay the same
  18. 18.⚡ A device works on 24 V and takes 0.2 A. What is its power (in watts)? =
  19. 19.🔺 A 2.2 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
  20. 20.📏 In the water-pipe picture of a circuit, current is like … (a) a narrow pipe (b) the pipe colour (c) the flow of water (d) the water pressure
  21. 21.📏 How many amperes (A) is 2020 mA? =
  22. 22.📏 Which unit measures current? (a) ohm (Ω) (b) watt (W) (c) volt (V) (d) ampere (A)
  23. 23.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  24. 24.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to make it brighter (c) to change its colour (d) to store charge
  25. 25.What does an LED do? (a) is a resistance knob (b) senses how hot it is (c) turns a fan or wheels (d) glows using little power
  26. 26.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
  27. 27.🔺 A 6 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
  28. 28.Which of these wastes electricity? (a) set the AC to 24 °C (b) unplug idle chargers (c) run fans in empty rooms (d) use LED lamps
  29. 29.🌈 A resistor has the colour bands grey, orange, black. What is its value (in ohms)?
  30. 30.🧮 Resistors of 20 Ω and 100 Ω are joined in series. What is the total resistance (in ohms)?
  31. 31.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V × I (c) P = I ÷ V (d) P = V + I
  32. 32.What does a motor do? (a) turns a fan or wheels (b) is a resistance knob (c) stores a little charge (d) boosts a small signal
  33. 33.🔺 A current of 0.2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  34. 34.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
  35. 35.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a buzzer (c) a diode (d) a capacitor
  36. 36.🔺 A current of 50 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  37. 37.🧾 A 250 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
  38. 38.🌈 A resistor has the colour bands red, yellow, brown. What is its value (in ohms)?
  39. 39.🔺 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
  40. 40.⚡ Power tells us … (a) energy used each second (b) the length of a wire (c) the colour of light (d) the size of a cell

Answer key

  1. 18
  2. the one nearest an end
  3. True
  4. R = V ÷ I
  5. light-emitting diode
  6. 4400
  7. store charge briefly
  8. 9.9
  9. 20
  10. 1
  11. 20
  12. 20
  13. 88
  14. anode (+)
  15. gets smaller
  16. 290
  17. bigger
  18. 4.8
  19. 10
  20. the flow of water
  21. 2.02
  22. ampere (A)
  23. cathode (−)
  24. to limit the current
  25. glows using little power
  26. 230
  27. 20
  28. run fans in empty rooms
  29. 83
  30. 120
  31. P = V × I
  32. turns a fan or wheels
  33. 0.8
  34. 115
  35. a buzzer
  36. 200
  37. 1.5
  38. 240
  39. V = I × R
  40. energy used each second

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