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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 398 · 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: an LED glows using little power. (a) True (b) False
  2. 2.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  3. 3.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a diode (c) a buzzer (d) a resistor
  4. 4.True or false: the voltmeter measures current. (a) False (b) True
  5. 5.What does a thermistor do? (a) blows if current is high (b) glows using little power (c) is a resistance knob (d) senses how hot it is
  6. 6.🧩 Which part changes electrical energy into movement? (a) a resistor (b) an LED (c) a fuse (d) a motor
  7. 7.🔺 A current of 0.2 A flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
  8. 8.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) stays the same (c) gets smaller (d) gets bigger
  9. 9.🌈 In the resistor colour code, which number does brown stand for?
  10. 10.Which of these is measured in volts (V)? (a) the flow of charge (b) how much a part resists (c) the push of a cell (d) power
  11. 11.🔺 A current of 10 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  12. 12.🌈 A resistor has the colour bands violet, brown, red. What is its value (in ohms)?
  13. 13.True or false: energy used each second is measured in watts (W). (a) False (b) True
  14. 14.🔺 A current of 3 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.True or false: the push of a cell is measured in volts (V). (a) False (b) True
  16. 16.🧮 A 1.4 V battery is joined to 2 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
  17. 17.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  18. 18.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it lights brighter (c) it does not light (d) it changes colour
  19. 19.🔺 A 7.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  20. 20.🌈 A resistor has the colour bands brown, violet, red. What is its value (in ohms)?
  21. 21.📏 Which unit measures power? (a) ampere (A) (b) volt (V) (c) watt (W) (d) ohm (Ω)
  22. 22.🧾 A 500 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
  23. 23.🧮 A 470 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  24. 24.🔍 Which is the odd one out? (a) use daylight to read (b) use LED lamps (c) leave fridge door open (d) close the fridge quickly
  25. 25.📏 How many ohms (Ω) is 9.2 kΩ?
  26. 26.⚡ A device works on 1.5 V and takes 0.5 A. What is its power (in watts)? =
  27. 27.🔺 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
  28. 28.🔺 A current of 2.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  29. 29.🌈 A resistor has the colour bands grey, orange, yellow. What is its value in kilo-ohms (kΩ)? =
  30. 30.⚡ A 9 W device works on 9 V. What current does it take (in amperes)? =
  31. 31.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to make it brighter (c) to limit the current (d) to store charge
  32. 32.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  33. 33.🔺 A current of 3 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  34. 34.🔺 A current of 10 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.🔺 A current of 3 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.🌈 A resistor has the colour bands green, yellow, red. What is its value in kilo-ohms (kΩ)? =
  37. 37.🌈 A resistor has the colour bands red, violet, red. What is its value (in ohms)?
  38. 38.🌈 A resistor has the colour bands brown, violet, orange. What is its value (in ohms)?
  39. 39.💡 Does it save or waste electricity to run fans in empty rooms? (a) wastes electricity (b) saves electricity
  40. 40.🔺 A current of 2.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =

Answer key

  1. True
  2. 500
  3. a buzzer
  4. False
  5. senses how hot it is
  6. a motor
  7. 5
  8. gets smaller
  9. 1
  10. the push of a cell
  11. 3.3
  12. 7100
  13. True
  14. 36
  15. True
  16. 0.1
  17. 345
  18. it does not light
  19. 50
  20. 1700
  21. watt (W)
  22. 1
  23. 475
  24. leave fridge door open
  25. 9200
  26. 0.75
  27. V = I × R
  28. 12.5
  29. 830
  30. 1
  31. to limit the current
  32. anode (+)
  33. 45
  34. 1.5
  35. 30
  36. 5.4
  37. 2700
  38. 17000
  39. wastes electricity
  40. 7.5

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