Q. The peak value of an alternating emf E given by $E = E_{0}\cos{\omega t}$ is 10 V and its frequency is 50 Hz. At a time $t = \frac{1}{100}s$, the instantaneous value of the emf is
A) 10 V
B) $5\sqrt{3}\ V$
C) 5 V
D) 1 V
Explanation
(b) $E = E_{0}\cos{\omega t = 10\cos{(2\pi \times ft)}}$
$= 10\cos\left( 2\pi \times 50 \times \frac{1}{600} \right)$
$= 10\cos\left( \frac{\pi}{6} \right) = 10 \times \frac{\sqrt{3}}{2} = 5\sqrt{3}\ V$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.