question_answer

Cell having an emf \[\varepsilon \] and internal resistance r is As the resistance R is increased, the plot of potential difference V across R is given by:

A)

B)

C)

D)

Correct Answer: C

Solution :

[c] The current through the resistance R \[I=\left( \frac{\varepsilon }{R+r} \right)\] The potential difference across R, \[V=IR=\left( \frac{\varepsilon }{R+r} \right)R\] Thus V increases as R increases up to certain limit, but it does not increase further.