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Electronics Worksheet: Ohm’s Law – Current and Resistance

Electronics lesson 13: Ohm’s law: find current and resistance · Set 234 · 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 20 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  2. 2.🔺 A 3 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
  3. 3.🔺 In the V-I-R triangle, how do we find V? (a) V = I × R (b) V = I + R (c) V = R ÷ I (d) V = I ÷ R
  4. 4.🔺 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
  5. 5.🔺 A current of 40 mA flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  6. 6.🔺 A current of 0.25 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  7. 7.🔺 A current of 25 mA flows when 12.5 V is joined across a resistor. What is its resistance (in ohms)?
  8. 8.🔺 A current of 40 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  9. 9.🔺 A current of 20 mA flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  10. 10.🔺 A 12 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  11. 11.🔺 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
  12. 12.🔺 A 2 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  13. 13.🔺 A 30 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  14. 14.🔺 A 23.5 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  15. 15.🔺 A current of 0.25 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
  16. 16.🔺 A 6.6 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
  17. 17.🔺 A 4.7 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  18. 18.🔺 A 5 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  19. 19.🔺 A current of 1 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  20. 20.🔺 A current of 2.5 A flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  21. 21.🔺 A current of 10 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  22. 22.🔺 A current of 25 mA flows when 3.75 V is joined across a resistor. What is its resistance (in ohms)?
  23. 23.🔺 A current of 2 A flows when 40 V is joined across a resistor. What is its resistance (in ohms)?
  24. 24.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) stays the same (c) gets smaller (d) becomes zero
  25. 25.🔺 A 0.6 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  26. 26.🔺 An 11.75 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  27. 27.🔺 A 7.5 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  28. 28.🔺 A current of 0.5 A flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  29. 29.🔺 A 0.8 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  30. 30.🔺 A current of 0.1 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  31. 31.🔺 A 2.5 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  32. 32.🔺 A 5 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  33. 33.🔺 A 1 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  34. 34.🔺 A current of 0.5 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  35. 35.🔺 A current of 10 mA flows when 2.2 V is joined across a resistor. What is its resistance (in ohms)?
  36. 36.🔺 A current of 50 mA flows when 23.5 V is joined across a resistor. What is its resistance (in ohms)?
  37. 37.🔺 A 3 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  38. 38.🔺 A current of 0.1 A flows when 0.4 V is joined across a resistor. What is its resistance (in ohms)?
  39. 39.🔺 A 12 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
  40. 40.🔺 A current of 40 mA flows when 8.8 V is joined across a resistor. What is its resistance (in ohms)?

Answer key

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

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