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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 818 · 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.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = I × R (c) V = R ÷ I (d) V = I ÷ R
  2. 2.🔺 A 2.2 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
  3. 3.⚡ A 12 W device works on 24 V. What current does it take (in amperes)? =
  4. 4.🔺 A current of 2.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  5. 5.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 3 V supply. What current flows (in mA)?
  6. 6.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
  7. 7.🧾 A 500 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
  8. 8.🔺 A current of 1.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  9. 9.💡 A red LED uses 2 V and should get 25 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  10. 10.🌈 In the resistor colour code, which number does grey stand for?
  11. 11.🌈 A resistor has the colour bands orange, red, red. What is its value (in ohms)?
  12. 12.⚡ A device works on 1.5 V and takes 0.1 A. What is its power (in watts)? =
  13. 13.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 87 Ω resistor? (a) grey-violet-black (b) grey-violet-brown (c) white-violet-black (d) violet-grey-black
  14. 14.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  15. 15.🔺 A current of 25 mA flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
  16. 16.📏 How many milliamperes (mA) is 0.14 A?
  17. 17.🔺 A current of 1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  18. 18.🧮 A 10 Ω resistor is joined in series with two equal 40 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  19. 19.💡 A red LED uses 2 V and should get 25 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
  20. 20.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  21. 21.True or false: the ammeter measures voltage. (a) True (b) False
  22. 22.🔺 A current of 0.5 A flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
  23. 23.Which of these is measured in amperes (A)? (a) the push of a cell (b) power (c) voltage (d) current
  24. 24.🔺 A current of 0.25 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.🧮 A 330 Ω resistor is joined in series with two equal 40 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  26. 26.🧮 A 33 Ω resistor is joined in series with two equal 100 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  27. 27.📏 Which unit measures the push of a cell? (a) ohm (Ω) (b) watt (W) (c) ampere (A) (d) volt (V)
  28. 28.🔺 A current of 20 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  29. 29.🧮 A 100 Ω resistor is joined in series with two equal 470 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  30. 30.🔺 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
  31. 31.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 10 (b) 100 (c) 1000 (d) 1024
  32. 32.💡 What does LED stand for? (a) low energy device (b) large electric dial (c) light energy dial (d) light-emitting diode
  33. 33.🧮 A 20 Ω resistor is joined in series with two equal 1000 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  34. 34.🔺 A current of 0.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.🧩 Which part changes electrical energy into sound? (a) a buzzer (b) a resistor (c) a capacitor (d) a diode
  36. 36.🔺 A current of 20 mA flows when 8 V is joined across a resistor. What is its resistance (in ohms)?
  37. 37.True or false: the ammeter measures current. (a) False (b) True
  38. 38.🔺 A current of 20 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  39. 39.⚡ Power tells us … (a) the length of a wire (b) energy used each second (c) the colour of light (d) the size of a cell
  40. 40.📏 How many milliamperes (mA) make 1 ampere? (a) 100 (b) 1000 (c) 60 (d) 10

Answer key

  1. V = I × R
  2. 10
  3. 0.5
  4. 20
  5. 5
  6. 230
  7. 2.5
  8. 30
  9. 120
  10. 8
  11. 3200
  12. 0.15
  13. grey-violet-black
  14. anode (+)
  15. 100
  16. 140
  17. 20
  18. 30
  19. 400
  20. 1.2
  21. False
  22. 8
  23. current
  24. 1.5
  25. 350
  26. 83
  27. volt (V)
  28. 6
  29. 335
  30. gets smaller
  31. 1000
  32. light-emitting diode
  33. 520
  34. 10
  35. a buzzer
  36. 400
  37. True
  38. 6.6
  39. energy used each second
  40. 1000

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