Question

The equation of A.C. current of frequency $75Hz$, if its RMS value is $20A$, is :

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

Answer 1

The correct option is B $I=20\sqrt{2}\sin \left(150\pi t\right)$

$w=2\pi f$

$w=150\pi$

$I_{rms}=20=\frac{I_o}{\sqrt{2}}$

$I_o=20\sqrt{2}$

$I=20\sqrt{2}sin\left(150\pi t\right)$