Question

If the potential difference between points $A$ and $B$ at a certain instant is $12\text{V}$, the potential difference between $A$ and $C$ at the same instant will be -

• A. $12\text{V}$
• B. $24\text{V}$
• C. $36\text{V}$
• D. $48\text{V}$

Answer 1

The correct option is C $36\text{V}$


The equivalent inductance between points $A$ and $B$ will be,

$L_{\text{eq}}=\frac{L_1{L}_2}{L_1+L_2}=\frac{4\times 12}{4+12}=3\text{H}$

So,

Potential difference between points $A$ and $B$ will be,

$V_{AB}=L_{\text{eq}}\frac{di}{dt}$

$\Rightarrow 12=3\times \frac{di}{dt}$

$\Rightarrow \frac{di}{dt}=4\text{A/s}\left[\text{At given instant}\right]$

At the same instant, the potential difference between points $A$ and $C$ will be,

$V_{AC}=L_{\text{eq}}\frac{di}{dt}$

$\Rightarrow V_{AC}=(3+6)\times 4=36\text{V}$