The potential difference V and the current I flowing through an instrument in an ac circuit of frequency f are given by V ` 5 cos omega t` volts and I = 2 sin `omegat` amperes (where `omega = 2pif`) . The power dissipated in the instrument is :

Options

A. zero
B. 10 watt
C. 5 watt
D. 2.5 watt

Answer

1

Explanation

As` V=5 cos (2 pift)=5 sin (2 pift + pi//2)`
And I=2 sin (2 pift)therefore
phase difference between V and Iis`phi =(pi)/(2)`
Average power` P = V_(rms)I_(rms)xx cosphi = 0`