Figure 7 8(b) shows the variation of voltage and current
with time We see that the current reaches its maximum value earlier than
the voltage by one-fourth of a period The instantaneous power supplied to the capacitor is
pc = i v = im cos(wt)vm sin(wt)
    = imvm cos(wt) sin(wt)
    
sin(2
)
2
m
i vm
ωt
=
(7