A cell of emf `E` has an internal resistance `r` and is connected to rheostat. When resistance `R` of rheostat is changed, correct graph of potentail difference across it is

Options

A.
B.
C.
D.

Answer

D

Explanation

(d) `V = IR = (ER)/(R + r) impliesV = (E)/(1 + r//R)`

So as `R` increases, `V` also increases. At `R = 0, V = 0`
But Maximum value of `V` can be `E` for `R = prop` so the graph can be as drawn below.