Question

The current flowing through an $ac$ circuit is given by $I=5sin\left(120\pi t\right)\text{A}$. How long will the current take to reach the peak value at the earliest starting from zero?

• A. $60\text{s}$
• B. $\frac{1}{120}\text{s}$
• C. $\frac{1}{60}\text{s}$
• D. $\frac{1}{240}\text{s}$

Answer 1

The correct option is D $\frac{1}{240}\text{s}$

$\omega =120\pi$
$\Rightarrow T=\frac{1}{60}\text{s}$
The current will take its peak value in $\frac{T}{4}$ time.
So $t=\frac{T}{4}=\frac{1}{240}\text{s}$