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Electronics Worksheet: Ohm’s Law – Current and Resistance

Electronics lesson 13: Ohm’s law: find current and resistance · Set 347 · 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 20 mA flows when 8 V is joined across a resistor. What is its resistance (in ohms)?
  2. 2.🔺 A current of 0.2 A flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
  3. 3.🔺 A 3 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  4. 4.🔺 A 1.6 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  5. 5.🔺 A 3.75 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  6. 6.🔺 A current of 20 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  7. 7.🔺 A current of 0.1 A flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
  8. 8.🔺 A current of 25 mA flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
  9. 9.🔺 A current of 10 mA flows when 2.2 V is joined across a resistor. What is its resistance (in ohms)?
  10. 10.🔺 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
  11. 11.🔺 A current of 20 mA flows when 4.4 V is joined across a resistor. What is its resistance (in ohms)?
  12. 12.🔺 A current of 50 mA flows when 25 V is joined across a resistor. What is its resistance (in ohms)?
  13. 13.🔺 A 6 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
  14. 14.🔺 A current of 40 mA flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  15. 15.🔺 A 25 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  16. 16.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V × R (c) I = V ÷ R (d) I = V + R
  17. 17.🔺 A 0.3 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  18. 18.🔺 A 7.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  19. 19.🔺 A current of 50 mA flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
  20. 20.🔺 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
  21. 21.🔺 A 3 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  22. 22.🔺 A current of 2.5 A flows when 25 V is joined across a resistor. What is its resistance (in ohms)?
  23. 23.🔺 A current of 1 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  24. 24.🔺 A current of 10 mA flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  25. 25.🔺 An 8 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  26. 26.🔺 A 16 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  27. 27.🔺 A 1.5 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  28. 28.🔺 A current of 1.5 A flows when 12 V is joined across a resistor. What is its resistance (in ohms)?
  29. 29.🔺 A current of 0.1 A flows when 0.2 V is joined across a resistor. What is its resistance (in ohms)?
  30. 30.🔺 A current of 40 mA flows when 4.8 V is joined across a resistor. What is its resistance (in ohms)?
  31. 31.🔺 A current of 10 mA flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
  32. 32.🔺 A 24 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  33. 33.🔺 A 6 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  34. 34.🔺 A current of 2 A flows when 30 V is joined across a resistor. What is its resistance (in ohms)?
  35. 35.🔺 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
  36. 36.🔺 A 4 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  37. 37.🔺 A 1.2 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  38. 38.🔺 A current of 25 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  39. 39.🔺 A 7.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  40. 40.🔺 A current of 40 mA flows when 13.2 V is joined across a resistor. What is its resistance (in ohms)?

Answer key

  1. 400
  2. 20
  3. 0.2
  4. 0.2
  5. 0.25
  6. 250
  7. 15
  8. 100
  9. 220
  10. gets smaller
  11. 220
  12. 500
  13. 20
  14. 150
  15. 2.5
  16. I = V ÷ R
  17. 0.1
  18. 0.5
  19. 150
  20. V = I × R
  21. 0.5
  22. 10
  23. 2
  24. 300
  25. 1
  26. 2
  27. 0.25
  28. 8
  29. 2
  30. 120
  31. 100
  32. 2
  33. 1
  34. 15
  35. R = V ÷ I
  36. 10
  37. 0.2
  38. 200
  39. 50
  40. 330

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