Question

An alternation current source of frequency $100Hz$ is joined to a combination of a resistance, a capacitance and a coil in series. The potential difference across the coil, the resistance and the capacitor is $46,8$ and $40$ volt respectively. The electromotive force of alternating current source in volt is

• A. $76$
• B. $10$
• C. $14$
• D. $94$

Answer 1

The correct option is B $10$

Calculation of emf:
Given $V_L=46V,V_R=8V$  and  $V_C=40V$

We know that
Emf $\left(E\right)=\sqrt{(V_R^2+(V_L-V_C{)}^2)}$
$E=\sqrt{(8{)}^2+(46-40{)}^2}$
$E=\sqrt{64+36}=\sqrt{100}$
$E=10V$
Hence, option $\left(C\right)$ is correct.