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Electronics Worksheet: Ohm’s Law – Current and Resistance

Electronics lesson 13: Ohm’s law: find current and resistance · Set 23 · 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.🔺 An 18 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  2. 2.🔺 A current of 0.25 A flows when 0.5 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 = I ÷ V (b) R = V + I (c) R = V × I (d) R = V ÷ I
  4. 4.🔺 In the V-I-R triangle, how do we find V? (a) V = I × R (b) V = R ÷ I (c) V = I ÷ R (d) V = I + R
  5. 5.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) gets bigger (c) stays the same (d) becomes zero
  6. 6.🔺 A current of 3 A flows when 15 V is joined across a resistor. What is its resistance (in ohms)?
  7. 7.🔺 A 30 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  8. 8.🔺 A current of 0.1 A flows when 0.2 V is joined across a resistor. What is its resistance (in ohms)?
  9. 9.🔺 A 7.5 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
  10. 10.🔺 A current of 0.25 A flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  11. 11.🔺 A 30 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  12. 12.🔺 A current of 0.25 A flows when 1.25 V is joined across a resistor. What is its resistance (in ohms)?
  13. 13.🔺 A current of 0.1 A flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
  14. 14.🔺 A 4 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  15. 15.🔺 A current of 1.5 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  16. 16.🔺 A 3.3 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
  17. 17.🔺 A 3.75 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  18. 18.🔺 A 5.5 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
  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 2 A flows when 12 V is joined across a resistor. What is its resistance (in ohms)?
  21. 21.🔺 A 30 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  22. 22.🔺 A 30 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  23. 23.🔺 A 2.5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
  24. 24.🔺 A 5 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  25. 25.🔺 A 6.6 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
  26. 26.🔺 A current of 2.5 A flows when 25 V is joined across a resistor. What is its resistance (in ohms)?
  27. 27.🔺 A 1.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  28. 28.🔺 An 8.25 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
  29. 29.🔺 A current of 0.1 A flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
  30. 30.🔺 A current of 10 mA flows when 3.3 V is joined across a resistor. What is its resistance (in ohms)?
  31. 31.🔺 A 15 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  32. 32.🔺 A 2.4 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  33. 33.🔺 A 3 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  34. 34.🔺 A current of 20 mA flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
  35. 35.🔺 A current of 20 mA flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  36. 36.🔺 A current of 40 mA flows when 8.8 V is joined across a resistor. What is its resistance (in ohms)?
  37. 37.🔺 A 7.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  38. 38.🔺 A current of 0.2 A flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
  39. 39.🔺 A current of 25 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  40. 40.🔺 A 1 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?

Answer key

  1. 1.5
  2. 2
  3. R = V ÷ I
  4. V = I × R
  5. gets smaller
  6. 5
  7. 2
  8. 2
  9. 25
  10. 20
  11. 3
  12. 5
  13. 10
  14. 10
  15. 4
  16. 10
  17. 25
  18. 25
  19. I = V ÷ R
  20. 6
  21. 2.5
  22. 1.5
  23. 10
  24. 2.5
  25. 20
  26. 10
  27. 0.1
  28. 25
  29. 12
  30. 330
  31. 3
  32. 0.2
  33. 0.2
  34. 200
  35. 300
  36. 220
  37. 50
  38. 5
  39. 400
  40. 10

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