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) KEY CONCEPT : The current in RC circuit is given by
`I = I_0e^(-t//RC)`
or `lnI = lnI_0 - t/(RC) or lnI = (-t/(RC)) + lnI_0`
`lnI = (-t/(RC)) + ln (E_0/R)`
On comparing with `y = mx +C`
Intercept = `ln (E_0/R) and slope = -1/(RC)`
When R is changedto 2R then slope increases and current becomes less. New graph is Q.