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Electronics Worksheet: Ohm’s Law – Current and Resistance

Electronics lesson 13: Ohm’s law: find current and resistance · Set 2 · 40 questions
TalentJR

Remember (Cover what you want): I = V ÷ R (amperes = volts ÷ ohms). R = V ÷ I (ohms = volts ÷ amperes); use amperes, not mA, in the formula. Example: 5 V and 25 mA (0.025 A) → R = 5 ÷ 0.025 = 200 Ω.

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  1. 1.🔺 A 9.4 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  2. 2.🔺 A current of 20 mA flows when 9.4 V is joined across a resistor. What is its resistance (in ohms)?
  3. 3.🔺 A 3 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  4. 4.🔺 A current of 10 mA flows when 3.3 V is joined across a resistor. What is its resistance (in ohms)?
  5. 5.🔺 A current of 2 A flows when 40 V is joined across a resistor. What is its resistance (in ohms)?
  6. 6.🔺 A 16 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  7. 7.🔺 A current of 40 mA flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
  8. 8.🔺 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
  9. 9.🔺 A 12 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  10. 10.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) gets smaller (c) becomes zero (d) stays the same
  11. 11.🔺 A 30 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  12. 12.🔺 A 0.3 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  13. 13.🔺 A 10 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  14. 14.🔺 A current of 2.5 A flows when 30 V is joined across a resistor. What is its resistance (in ohms)?
  15. 15.🔺 A current of 10 mA flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
  16. 16.🔺 A current of 20 mA flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  17. 17.🔺 A current of 50 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  18. 18.🔺 A 4 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  19. 19.🔺 A current of 3 A flows when 15 V is joined across a resistor. What is its resistance (in ohms)?
  20. 20.🔺 A current of 10 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  21. 21.🔺 A 20 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  22. 22.🔺 A current of 50 mA flows when 25 V is joined across a resistor. What is its resistance (in ohms)?
  23. 23.🔺 A current of 25 mA flows when 12.5 V is joined across a resistor. What is its resistance (in ohms)?
  24. 24.🔺 A 6 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
  25. 25.🔺 A 20 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  26. 26.🔺 A 4 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  27. 27.🔺 A 7.5 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
  28. 28.🔺 A 2.5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
  29. 29.🔺 A 30 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  30. 30.🔺 A 50 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  31. 31.🔺 A current of 20 mA flows when 4.4 V is joined across a resistor. What is its resistance (in ohms)?
  32. 32.🔺 A current of 25 mA flows when 11.75 V is joined across a resistor. What is its resistance (in ohms)?
  33. 33.🔺 A 6 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  34. 34.🔺 A 6 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  35. 35.🔺 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
  36. 36.🔺 A current of 1 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  37. 37.🔺 A current of 0.2 A flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
  38. 38.🔺 A 30 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  39. 39.🔺 A current of 3 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  40. 40.🔺 A 5 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =

Answer key

  1. 20
  2. 470
  3. 0.25
  4. 330
  5. 20
  6. 40
  7. 500
  8. V = I × R
  9. 1
  10. gets smaller
  11. 2
  12. 0.1
  13. 2
  14. 12
  15. 100
  16. 300
  17. 100
  18. 10
  19. 5
  20. 200
  21. 2.5
  22. 500
  23. 500
  24. 20
  25. 1
  26. 40
  27. 25
  28. 10
  29. 1.5
  30. 2.5
  31. 220
  32. 470
  33. 3
  34. 50
  35. R = V ÷ I
  36. 3
  37. 5
  38. 2.5
  39. 2
  40. 2.5

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