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Electronics Worksheet: Ohm’s Law – Current and Resistance

Electronics lesson 13: Ohm’s law: find current and resistance · Set 938 · 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 2.5 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  2. 2.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V + R (c) I = V ÷ R (d) I = R ÷ V
  3. 3.🔺 A current of 40 mA flows when 16 V is joined across a resistor. What is its resistance (in ohms)?
  4. 4.🔺 A current of 25 mA flows when 6.25 V is joined across a resistor. What is its resistance (in ohms)?
  5. 5.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = V + I (c) R = I ÷ V (d) R = V ÷ I
  6. 6.🔺 A 2.5 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  7. 7.🔺 A current of 0.25 A flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
  8. 8.🔺 A current of 25 mA flows when 8.25 V is joined across a resistor. What is its resistance (in ohms)?
  9. 9.🔺 A 2.2 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
  10. 10.🔺 A 10 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  11. 11.🔺 A 30 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  12. 12.🔺 A 3 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
  13. 13.🔺 A current of 25 mA flows when 11.75 V is joined across a resistor. What is its resistance (in ohms)?
  14. 14.🔺 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
  15. 15.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets bigger (c) stays the same (d) gets smaller
  16. 16.🔺 A 23.5 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  17. 17.🔺 A current of 20 mA flows when 2.4 V is joined across a resistor. What is its resistance (in ohms)?
  18. 18.🔺 A 20 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  19. 19.🔺 A current of 2 A flows when 16 V is joined across a resistor. What is its resistance (in ohms)?
  20. 20.🔺 A 12.5 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  21. 21.🔺 A 5 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
  22. 22.🔺 A current of 0.1 A flows when 0.2 V is joined across a resistor. What is its resistance (in ohms)?
  23. 23.🔺 A current of 3 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  24. 24.🔺 A 1.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  25. 25.🔺 A 0.4 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  26. 26.🔺 A 6 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  27. 27.🔺 An 8 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  28. 28.🔺 A current of 10 mA flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
  29. 29.🔺 A 10 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  30. 30.🔺 A current of 50 mA flows when 11 V is joined across a resistor. What is its resistance (in ohms)?
  31. 31.🔺 A 0.6 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  32. 32.🔺 A current of 40 mA flows when 18.8 V is joined across a resistor. What is its resistance (in ohms)?
  33. 33.🔺 A 3.3 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
  34. 34.🔺 A 0.4 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  35. 35.🔺 A current of 20 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  36. 36.🔺 A 1.6 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  37. 37.🔺 A 6 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  38. 38.🔺 A current of 20 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  39. 39.🔺 A 1.25 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  40. 40.🔺 An 8 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?

Answer key

  1. 25
  2. I = V ÷ R
  3. 400
  4. 250
  5. R = V ÷ I
  6. 0.25
  7. 4
  8. 330
  9. 10
  10. 20
  11. 2
  12. 10
  13. 470
  14. V = I × R
  15. gets smaller
  16. 50
  17. 120
  18. 50
  19. 8
  20. 2.5
  21. 25
  22. 2
  23. 2
  24. 10
  25. 0.1
  26. 0.5
  27. 2
  28. 150
  29. 2.5
  30. 220
  31. 0.2
  32. 470
  33. 10
  34. 0.2
  35. 500
  36. 0.2
  37. 1.5
  38. 250
  39. 0.25
  40. 40

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