Question

find the power delivered to an element at t= 5ms if the current entering its positive terminal is i= 5cos60πt Amp and the voltage is (a) v = 3i (b) V= 3di/dt

Answer 1

a. --- power = i V= 5 cos (60 pi t ) * 15 cos (60 pi t)
= 75 cos^2 (60 pi t)

b. --- power = i V = 5 cos (60 pi t) * 3 * [ - 5*60 * pi sin (60 pi t) ]
= - 4500 pi * [ sin (60 pi t) * cos (60 pi t) ]