not mean that the average power consumed is zero and
that there is no dissipation of electrical energy As you
know, Joule heating is given by i2R and depends on i2
(which is always positive whether i is positive or negative)
and not on i Thus, there is Joule heating and
dissipation 
of 
electrical 
energy 
when 
an
ac current passes through a resistor The instantaneous power dissipated in the resistor is
2
2
sin2
m
p
i R
i R
ωt
=
=
(7