Question

The current in an AC circuit is represented by $i=5sin(300t-\frac{\pi }{4})$
where, t is in seconds and current is in amperes. Then, the frequency of AC is

• A. 50 Hz
• B. 47.75 Hz
• C. 30 Hz
• D. 25 Hz

Answer 1

The correct option is B 47.75 Hz

The standard equation of current for AC is
$i-i_{0}sin(\omega t\pm \varphi )$ (i)
Given, $i=5sin(300t-\frac{\pi }{4})$ (ii)
Comparing the two equations, we get
$\omega =300rad/s,f=\frac{\omega }{2\pi }=\frac{300}{2\pi }$
$\Rightarrow f=47.75Hz$