Question

The equation of current in a purely inductive circuit is $5 \sin \left(49 \pi t -30^{\circ}\right)$. If the inductance is $30\, mH$ then the equation for the voltage across the inductor, will be:
$\left\{\text { Let } \pi=\frac{22}{7}\right\}$

• A. $1.47 \sin \left(49 \pi t -30^{\circ}\right)$
• B. $1.47 \sin \left(49 \pi t +60^{\circ}\right)$
• C. $23.1 \sin \left(49 \pi t -30^{\circ}\right)$
• D. $23.1 \sin \left(49 \pi t+60^{\circ}\right)$

Answer 1

Answer: (D)

$v_0=i_0 x_L $
$=i_0(w L)$
$=(5)(49 \pi)\left(30 \times 10^{-3}\right)$
$ =23.1$
Voltage will lead current by $90^{\circ}$.
$\therefore V =23.1 \sin \left(49 \pi t +60^{\circ}\right)$