Question

What will be the equation of ac of frequency 75 Hz if its r.m.s. value is 20 A

• A. $i = 20\sin 150\pi t$
• B. $\mathbf{i = 20}\sqrt{\mathbf{2}}\mathbf{\sin}\mathbf{(}\mathbf{150\pi t)}$
• C. $i = \frac{20}{\sqrt{2}}\sin(150\pi t)$
• D. $i = 20\sqrt{2}\sin(75\pi t)$

Answer 1

Answer: (B)

$\mathbf{i = 20}\sqrt{\mathbf{2}}\mathbf{\sin}\mathbf{(}\mathbf{150\pi t)}$

Answer 2

By using $i = i_{0}\sin\omega t = i_{0}\sin 2\pi\nu t = i_{rms}\sqrt{2}\sin 2\pi\nu t$

⇒ $i = 20\sqrt{2}\sin(150\pi t)$.