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Electronics Worksheet: Ohm’s Law – Current and Resistance

Electronics lesson 13: Ohm’s law: find current and resistance · Set 254 · 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 0.5 A flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
  2. 2.🔺 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
  3. 3.🔺 A current of 0.1 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  4. 4.🔺 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
  5. 5.🔺 A 30 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  6. 6.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = R ÷ V (c) I = V ÷ R (d) I = V × R
  7. 7.🔺 A current of 2 A flows when 12 V is joined across a resistor. What is its resistance (in ohms)?
  8. 8.🔺 A 2.5 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  9. 9.🔺 A current of 1.5 A flows when 18 V is joined across a resistor. What is its resistance (in ohms)?
  10. 10.🔺 A current of 0.1 A flows when 0.4 V is joined across a resistor. What is its resistance (in ohms)?
  11. 11.🔺 A 30 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  12. 12.🔺 A 40 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  13. 13.🔺 A current of 40 mA flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
  14. 14.🔺 A 3 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  15. 15.🔺 A 0.6 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  16. 16.🔺 A 3 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  17. 17.🔺 A current of 0.25 A flows when 3.75 V is joined across a resistor. What is its resistance (in ohms)?
  18. 18.🔺 A 12 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  19. 19.🔺 A current of 0.5 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
  20. 20.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) gets bigger (c) becomes zero (d) stays the same
  21. 21.🔺 An 11.75 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  22. 22.🔺 A 1 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  23. 23.🔺 A 5 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  24. 24.🔺 A 1 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  25. 25.🔺 A current of 0.2 A flows when 2.4 V is joined across a resistor. What is its resistance (in ohms)?
  26. 26.🔺 A current of 20 mA flows when 4.4 V is joined across a resistor. What is its resistance (in ohms)?
  27. 27.🔺 A 15 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
  28. 28.🔺 A current of 50 mA flows when 15 V is joined across a resistor. What is its resistance (in ohms)?
  29. 29.🔺 A 4.7 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  30. 30.🔺 A 3 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  31. 31.🔺 A current of 0.5 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  32. 32.🔺 A current of 25 mA flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  33. 33.🔺 A 1 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  34. 34.🔺 A current of 40 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  35. 35.🔺 A 1.6 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  36. 36.🔺 A 0.6 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  37. 37.🔺 A current of 2.5 A flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
  38. 38.🔺 A current of 20 mA flows when 9.4 V is joined across a resistor. What is its resistance (in ohms)?
  39. 39.🔺 A 3 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  40. 40.🔺 A 1.5 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =

Answer key

  1. 15
  2. V = I × R
  3. 20
  4. R = V ÷ I
  5. 1.5
  6. I = V ÷ R
  7. 6
  8. 25
  9. 12
  10. 4
  11. 2
  12. 2
  13. 500
  14. 0.25
  15. 0.1
  16. 0.5
  17. 15
  18. 1.5
  19. 3
  20. gets smaller
  21. 25
  22. 10
  23. 50
  24. 0.25
  25. 12
  26. 220
  27. 50
  28. 300
  29. 10
  30. 25
  31. 12
  32. 120
  33. 0.5
  34. 250
  35. 0.2
  36. 0.2
  37. 8
  38. 470
  39. 1.5
  40. 0.5

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