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MCQ practice · SSC Physics Board questions · Chapter 11: Current Electricity

Chattogram Board 2021

Regarding potential difference, resistance and electric current-

  1. i. the smaller the potential difference, the smaller the current
  2. ii. when the potential difference is negative the current changes its direction
  3. iii. the larger the resistance, the smaller the current

Think it through first, then pick an option.

  1. a i and ii
  2. b i and iii
  3. c ii and iii
  4. d i, ii and iii
Answer and explanation

Correct answer: d i, ii and iii

All three are true: I ∝ V, reversing the potential difference reverses the current, and a larger resistance gives less current.

Why the other options are wrong

  • a i and ii: i and ii: this leaves out iii. A larger resistance gives a smaller current, so iii is also true.
  • b i and iii: i and iii: this leaves out ii. Turning the batteries round reverses the potential difference and the current changes direction, so ii is true.
  • c ii and iii: ii and iii: this leaves out i. Since I ∝ V, a smaller potential difference gives a smaller current, so i is also true.