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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 486 · 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 formula gives electric power? (a) P = V × I (b) P = I ÷ V (c) P = V + I (d) P = V ÷ I
  2. 2.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 13 Ω resistor? (a) orange-brown-black (b) brown-orange-black (c) brown-orange-brown (d) red-orange-black
  3. 3.🧾 A 200 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
  4. 4.🧮 Four equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  5. 5.True or false: energy used each second is measured in watts (W). (a) False (b) True
  6. 6.🧩 Which component blows if current is high? (a) potentiometer (b) diode (c) resistor (d) fuse
  7. 7.⚡ A 9 W device works on 3 V. What current does it take (in amperes)? =
  8. 8.🧮 Five equal 25 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  9. 9.💡 Does it save or waste electricity to use LED lamps? (a) wastes electricity (b) saves electricity
  10. 10.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 88 Ω resistor? (a) white-grey-black (b) grey-grey-brown (c) grey-white-black (d) grey-grey-black
  11. 11.🔺 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
  12. 12.🌈 A resistor has the colour bands blue, yellow, yellow. What is its value in kilo-ohms (kΩ)? =
  13. 13.🔺 A current of 0.1 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  14. 14.🔺 A current of 25 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.🔺 A current of 1 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  16. 16.True or false: a resistor has coloured bands. (a) True (b) False
  17. 17.🌈 A resistor has the colour bands orange, blue, brown. What is its value (in ohms)?
  18. 18.🧮 Three equal 75 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  19. 19.🧮 Resistors of 47 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
  20. 20.🔺 A current of 50 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  21. 21.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a resistor (c) a diode (d) a buzzer
  22. 22.Which of these wastes electricity? (a) use LED lamps (b) set the AC to 24 °C (c) run fans in empty rooms (d) close the fridge quickly
  23. 23.💡 What does LED stand for? (a) light-emitting diode (b) light energy dial (c) large electric dial (d) low energy device
  24. 24.🔺 A current of 0.2 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.🧮 Two resistors in parallel give a total that is … (a) their sum (b) always zero (c) more than either one (d) less than either one
  26. 26.True or false: a motor turns a fan or wheels. (a) False (b) True
  27. 27.🧾 A 1000 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
  28. 28.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = R ÷ V (c) I = V ÷ R (d) I = V × R
  29. 29.💡 Does it save or waste electricity to use daylight to read? (a) saves electricity (b) wastes electricity
  30. 30.🔺 A current of 0.1 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  32. 32.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
  33. 33.💡 An LED is joined to a 9 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) may burn out (c) lights up
  34. 34.🌈 A resistor has the colour bands brown, violet, brown. What is its value (in ohms)?
  35. 35.💡 Does it save or waste electricity to close the fridge quickly? (a) wastes electricity (b) saves electricity
  36. 36.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) gets bigger (c) becomes zero (d) stays the same
  37. 37.🔺 In the V-I-R triangle, how do we find R? (a) R = V ÷ I (b) R = V + I (c) R = V × I (d) R = I ÷ V
  38. 38.🧩 A capacitor in a circuit can … (a) make light (b) store charge briefly (c) spin a wheel (d) measure heat
  39. 39.What does a resistor do? (a) smooths a wobbly supply (b) makes a beeping sound (c) boosts a small signal (d) limits the current
  40. 40.What does a capacitor do? (a) senses how hot it is (b) glows using little power (c) blows if current is high (d) smooths a wobbly supply

Answer key

  1. P = V × I
  2. brown-orange-black
  3. 0.8
  4. 5
  5. True
  6. fuse
  7. 3
  8. 5
  9. saves electricity
  10. grey-grey-black
  11. V = I × R
  12. 640
  13. 20
  14. 10
  15. 4
  16. True
  17. 360
  18. 25
  19. 67
  20. 5
  21. a buzzer
  22. run fans in empty rooms
  23. light-emitting diode
  24. 1
  25. less than either one
  26. True
  27. 6
  28. I = V ÷ R
  29. saves electricity
  30. 1
  31. 345
  32. 300
  33. may burn out
  34. 170
  35. saves electricity
  36. gets smaller
  37. R = V ÷ I
  38. store charge briefly
  39. limits the current
  40. smooths a wobbly supply

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