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Electronics Worksheet: Ohm’s Law – Current and Resistance

Electronics lesson 13: Ohm’s law: find current and resistance · Set 21 · 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.🔺 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
  2. 2.🔺 A current of 1 A flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
  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.🔺 A current of 0.1 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  5. 5.🔺 A 20 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  6. 6.🔺 A 1 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  7. 7.🔺 A 0.6 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  8. 8.🔺 A 5 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  9. 9.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets bigger (c) gets smaller (d) becomes zero
  10. 10.🔺 A current of 40 mA flows when 8.8 V is joined across a resistor. What is its resistance (in ohms)?
  11. 11.🔺 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
  12. 12.🔺 A current of 2 A flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  13. 13.🔺 A current of 10 mA flows when 1.5 V is joined across a resistor. What is its resistance (in ohms)?
  14. 14.🔺 An 18.8 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  15. 15.🔺 A 20 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  16. 16.🔺 An 8 V supply is joined across a 4 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 0.8 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  19. 19.🔺 A current of 0.1 A flows when 0.5 V is joined across a resistor. What is its resistance (in ohms)?
  20. 20.🔺 An 11 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
  21. 21.🔺 A current of 2.5 A flows when 15 V is joined across a resistor. What is its resistance (in ohms)?
  22. 22.🔺 A 5 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  23. 23.🔺 A current of 50 mA flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  24. 24.🔺 A current of 10 mA flows when 2.2 V is joined across a resistor. What is its resistance (in ohms)?
  25. 25.🔺 A 4.7 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  26. 26.🔺 A 15 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  27. 27.🔺 A current of 40 mA flows when 12 V is joined across a resistor. What is its resistance (in ohms)?
  28. 28.🔺 A current of 2 A flows when 24 V is joined across a resistor. What is its resistance (in ohms)?
  29. 29.🔺 A current of 40 mA flows when 8 V is joined across a resistor. What is its resistance (in ohms)?
  30. 30.🔺 A current of 25 mA flows when 8.25 V is joined across a resistor. What is its resistance (in ohms)?
  31. 31.🔺 A current of 20 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  32. 32.🔺 A current of 10 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  33. 33.🔺 A 25 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  34. 34.🔺 A 5 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  35. 35.🔺 A current of 2 A flows when 40 V is joined across a resistor. What is its resistance (in ohms)?
  36. 36.🔺 A 7.5 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  37. 37.🔺 A 12.5 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  38. 38.🔺 A current of 50 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  39. 39.🔺 A 0.2 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  40. 40.🔺 A 0.6 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =

Answer key

  1. R = V ÷ I
  2. 20
  3. V = I × R
  4. 20
  5. 40
  6. 0.1
  7. 0.2
  8. 10
  9. gets smaller
  10. 220
  11. I = V ÷ R
  12. 5
  13. 150
  14. 40
  15. 2
  16. 2
  17. 15
  18. 0.2
  19. 5
  20. 50
  21. 6
  22. 50
  23. 120
  24. 220
  25. 10
  26. 2.5
  27. 300
  28. 12
  29. 200
  30. 330
  31. 250
  32. 500
  33. 50
  34. 2.5
  35. 20
  36. 1.5
  37. 2.5
  38. 200
  39. 0.1
  40. 0.1

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