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Electronics Worksheet: Ohm’s Law – Current and Resistance

Electronics lesson 13: Ohm’s law: find current and resistance · Set 19 · 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 current of 25 mA flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
  2. 2.🔺 A 4 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  3. 3.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V × R (c) I = V ÷ R (d) I = V + R
  4. 4.🔺 A current of 0.25 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
  5. 5.🔺 An 11.75 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  6. 6.🔺 A 1 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  7. 7.🔺 A 3 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  8. 8.🔺 A current of 0.25 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  9. 9.🔺 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
  10. 10.🔺 A 1.25 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  11. 11.🔺 A 9 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  12. 12.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets bigger (c) gets smaller (d) becomes zero
  13. 13.🔺 A 3.75 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  14. 14.🔺 A 3 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  15. 15.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I ÷ R (c) V = I + R (d) V = I × R
  16. 16.🔺 A 4 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  17. 17.🔺 An 18 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  18. 18.🔺 A 12 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
  19. 19.🔺 A current of 1 A flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  20. 20.🔺 A 30 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  21. 21.🔺 A current of 20 mA flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  22. 22.🔺 A current of 1.5 A flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
  23. 23.🔺 A 2 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  24. 24.🔺 A current of 1 A flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  25. 25.🔺 A 6 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  26. 26.🔺 A 0.3 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  27. 27.🔺 A current of 20 mA flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  28. 28.🔺 A 40 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  29. 29.🔺 A current of 50 mA flows when 16.5 V is joined across a resistor. What is its resistance (in ohms)?
  30. 30.🔺 A 4.7 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  31. 31.🔺 A 2 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
  32. 32.🔺 A 12 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  33. 33.🔺 A 25 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  34. 34.🔺 A 4.8 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  35. 35.🔺 A 7.5 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  36. 36.🔺 A 12 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  37. 37.🔺 A current of 1 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  38. 38.🔺 A 5 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  39. 39.🔺 A current of 25 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  40. 40.🔺 A 2.4 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?

Answer key

  1. 300
  2. 10
  3. I = V ÷ R
  4. 6
  5. 25
  6. 0.5
  7. 25
  8. 12
  9. R = V ÷ I
  10. 0.25
  11. 3
  12. gets smaller
  13. 0.25
  14. 20
  15. V = I × R
  16. 1
  17. 3
  18. 40
  19. 10
  20. 3
  21. 150
  22. 5
  23. 0.25
  24. 5
  25. 3
  26. 0.1
  27. 300
  28. 2
  29. 330
  30. 10
  31. 10
  32. 1
  33. 2.5
  34. 40
  35. 2.5
  36. 3
  37. 2
  38. 0.5
  39. 400
  40. 20

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