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Electronics Worksheet: Ohm’s Law – Current and Resistance

Electronics lesson 13: Ohm’s law: find current and resistance · Set 327 · 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 2 A flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
  2. 2.🔺 A current of 0.1 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  3. 3.🔺 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
  4. 4.🔺 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
  5. 5.🔺 A current of 50 mA flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
  6. 6.🔺 A 30 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  7. 7.🔺 A 6 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  8. 8.🔺 A current of 10 mA flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
  9. 9.🔺 A 6 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  10. 10.🔺 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
  11. 11.🔺 A current of 50 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  12. 12.🔺 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
  13. 13.🔺 A 20 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  14. 14.🔺 A current of 10 mA flows when 3.3 V is joined across a resistor. What is its resistance (in ohms)?
  15. 15.🔺 A current of 10 mA flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
  16. 16.🔺 A 1 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  17. 17.🔺 A current of 3 A flows when 30 V is joined across a resistor. What is its resistance (in ohms)?
  18. 18.🔺 A 5 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  19. 19.🔺 A current of 50 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  20. 20.🔺 A current of 10 mA flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
  21. 21.🔺 A 1.5 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  22. 22.🔺 A current of 50 mA flows when 12.5 V is joined across a resistor. What is its resistance (in ohms)?
  23. 23.🔺 A current of 20 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  24. 24.🔺 A current of 10 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  25. 25.🔺 A current of 40 mA flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
  26. 26.🔺 A 7.5 V supply is joined across a 15 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.🔺 An 8 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
  29. 29.🔺 A 0.5 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  30. 30.🔺 A 23.5 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  31. 31.🔺 A current of 0.25 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
  32. 32.🔺 A 4 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  33. 33.🔺 A current of 10 mA flows when 4.7 V is joined across a resistor. What is its resistance (in ohms)?
  34. 34.🔺 An 11 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
  35. 35.🔺 A current of 25 mA flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
  36. 36.🔺 A 2 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  37. 37.🔺 A current of 3 A flows when 9 V is joined across a resistor. What is its resistance (in ohms)?
  38. 38.🔺 A 0.5 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  39. 39.🔺 A current of 0.1 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
  40. 40.🔺 A 2 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?

Answer key

  1. 10
  2. 20
  3. R = V ÷ I
  4. gets smaller
  5. 150
  6. 1.5
  7. 0.5
  8. 100
  9. 40
  10. V = I × R
  11. 100
  12. I = V ÷ R
  13. 50
  14. 330
  15. 250
  16. 0.2
  17. 10
  18. 0.5
  19. 200
  20. 120
  21. 0.25
  22. 250
  23. 100
  24. 500
  25. 500
  26. 0.5
  27. 300
  28. 40
  29. 0.25
  30. 50
  31. 6
  32. 0.5
  33. 470
  34. 50
  35. 300
  36. 0.25
  37. 3
  38. 0.1
  39. 15
  40. 10

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