A capcitor capacitance C is charged to a potential difference V and then connected in series with an open key and a pure resistor R. At time t = 0, the key is closed. If I is current at time t = 0, a plot of log I against t is shown in the graph (2). Later one of the parameters, i.e., V, R and C is changed, keeping the other two constant and graph (2) is recorded. Then

Options

A. `V_(0)` is decreased
B. R is decreased
C. R is increased
D. C is decreased

Answer

D

Explanation

`I=(V_(0))/(R)e^(-t//RC)`
`l nI=l n(V_(0))/(R)(t)/(RC)`
In both cases log of initial current is same that means `(V_(0))/(R)` is constant to keep `(V_(0))/(R)` constant both `V_(0))` and R have to be changed whereas it is stated that only one parameter out of `V_(0),R` and C is changed Therefore only C has been changed and to match the straight line the graph, it is decreased.