In the above problem if given graph is between `V_(AB)` and time. Then plot graph between `V_(ED)` and time.

Answer

A

Explanation

From `O` to `A` `V=at`
`:. At=q/C+iR`
Differentiating w.r.t time we have
`a=1/C((dq)/(dt))+((di)/(dt))R`
or `((di)/((dt))R R=a-i/C` (as `i=(dq)/(dt))`
`:. int_0^i (di)/(a-i//C)=int_0^1 (dt)/R`
`:. i=aC(1-e^(-t//CR))`

i.e. Curren in the circuit increases exponentially
`:. V_(ED)=iR=aCR(1-e^(-t//CR))`
or `V_(ED)` also increases exponentially

From `A` onwards When `V=constant` (say`V_0`)
`V_0=at` or `t=V_0/a`
`:. V_(ED)=aCR(1-e^(-V_0//aCR))`
After this `V_(ED)` will decrease exponentially.
Hence, a rough graph is as shown in figure.