Question

A capacitor is charged using an external battery with a resistance x in series. The dashed line showns the variation of In I with respect to time. If the resistance is changed to 2x, the new graph will be

A. P
B. Q
C. R
D. S

Answer 1

Correct Answer - B
b. The current in RC circuit is given by `I = I_0e^(-t//RC)`
or `1nI = 1nI_0 - t/(RC) = (-t)/(RC) + 1NI_0`
`=(-t/(RC))+1n(E_0)/R`
On comparing with `y = mx + C`, we get
Intercept `= 1n (E_0)/R and slope = -1/(RC)`
When R is changed to 2R, then slope decreases in magnitude.
New graph is Q.