An alternating voltage 
sin
=
ω
m
v
v
t  applied to a resistor R drives a
current i = im sinwt in the resistor, 
m
m
v
i
=R The current is in phase with
the applied voltage 2 For an alternating current i = im sin wt passing through a resistor R, the
average power loss P (averaged over a cycle) due to joule heating is
( 1/2 )i 2
mR