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Electronics Worksheet: Ohm’s Law – Current and Resistance

Electronics lesson 13: Ohm’s law: find current and resistance · Set 5 · 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 5 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  2. 2.🔺 A current of 3 A flows when 18 V is joined across a resistor. What is its resistance (in ohms)?
  3. 3.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) becomes zero (c) gets smaller (d) gets bigger
  4. 4.🔺 A 2.5 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  5. 5.🔺 A current of 3 A flows when 60 V is joined across a resistor. What is its resistance (in ohms)?
  6. 6.🔺 A current of 0.2 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  7. 7.🔺 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
  8. 8.🔺 A 40 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  9. 9.🔺 A 0.3 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  10. 10.🔺 A 1.25 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  11. 11.🔺 A 20 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  12. 12.🔺 A current of 3 A flows when 45 V is joined across a resistor. What is its resistance (in ohms)?
  13. 13.🔺 A 6 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  14. 14.🔺 A current of 10 mA flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
  15. 15.🔺 A 10 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  16. 16.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = I ÷ V (c) R = V + I (d) R = V ÷ I
  17. 17.🔺 A current of 40 mA flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
  18. 18.🔺 A current of 10 mA flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
  19. 19.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = V × R (c) I = R ÷ V (d) I = V ÷ R
  20. 20.🔺 A current of 20 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  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 50 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  23. 23.🔺 A 2.4 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  24. 24.🔺 A current of 3 A flows when 12 V is joined across a resistor. What is its resistance (in ohms)?
  25. 25.🔺 A 12.5 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  26. 26.🔺 A 5 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  27. 27.🔺 A 0.5 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  28. 28.🔺 An 18 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  29. 29.🔺 A current of 0.2 A flows when 0.6 V is joined across a resistor. What is its resistance (in ohms)?
  30. 30.🔺 A current of 50 mA flows when 23.5 V is joined across a resistor. What is its resistance (in ohms)?
  31. 31.🔺 A 15 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  32. 32.🔺 A current of 2.5 A flows when 30 V is joined across a resistor. What is its resistance (in ohms)?
  33. 33.🔺 A current of 50 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  34. 34.🔺 A 4 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  35. 35.🔺 A 20 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  36. 36.🔺 A 1.5 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  37. 37.🔺 A 6.25 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
  38. 38.🔺 An 8 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
  39. 39.🔺 A current of 0.2 A flows when 1.6 V is joined across a resistor. What is its resistance (in ohms)?
  40. 40.🔺 A current of 3 A flows when 30 V is joined across a resistor. What is its resistance (in ohms)?

Answer key

  1. 50
  2. 6
  3. gets smaller
  4. 25
  5. 20
  6. 10
  7. V = I × R
  8. 2
  9. 0.1
  10. 0.25
  11. 40
  12. 15
  13. 2
  14. 400
  15. 25
  16. R = V ÷ I
  17. 500
  18. 150
  19. I = V ÷ R
  20. 500
  21. 150
  22. 2.5
  23. 0.2
  24. 4
  25. 25
  26. 2.5
  27. 0.25
  28. 1.5
  29. 3
  30. 470
  31. 1
  32. 12
  33. 100
  34. 40
  35. 2.5
  36. 0.5
  37. 25
  38. 40
  39. 8
  40. 10

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