A graph of the current in an circuit during the discharge of a fully charged…

PHYSICS · Single correct · A Level · Physics · Fields and their consequences · Fields and their consequences

Problem

A graph of the current

I

in an

RC

circuit during the discharge of a fully charged capacitor is a smooth curve that starts at

I=I_0

when

t=0

and approaches zero as

t

increases. Which statement best describes the simultaneous graph of the voltage

V

across the capacitor? (a) It starts at

V=0

when

t=0

and rises exponentially toward

V_0

with the same time constant as the current. (b) It starts at

V=V_0

when

t=0

and decreases exponentially toward zero with the same time constant as the current. (c) It starts at

V=V_0

when

t=0

and decreases exponentially toward zero with a time constant equal to

2RC

.},{ (d) It starts at

V=V_0

when

t=0

and decreases linearly to zero exactly at

t=2RC