Physics - EMI/AC Question with Solution | TestHub

Induced emf,$\text{e}=-\text{L}\frac{\text{di}}{\text{dt}}$

For$0\le \text{t}\le \frac{\text{T}}{4}$,

i-t graph is a straight line with positive constant slope.

$\therefore \frac{\text{di}}{\text{dt}}=\text{constant}$

$\Rightarrow \text{e}=-\text{ve}$and constant For$0\le \text{t}\le \frac{\text{T}}{4}$

For$\frac{\text{T}}{4}\le \text{t}\le \frac{\text{T}}{2},$

$\because$i is constant$\therefore \frac{\text{di}}{\text{dt}}=0$

$\Rightarrow \text{e}=0$For$\frac{\text{T}}{4}\le \text{t}\le \frac{\text{T}}{2}$

For$\frac{\text{T}}{2}\le \text{t}\le \frac{3\text{T}}{4}$,

i-t graph is a straight line with negative constant slope.

$\therefore \frac{\text{di}}{\text{dt}}=\text{constant}$

⇒   e = + ve and constant     For$\frac{\text{T}}{2}\le \text{t}\le \frac{3\text{T}}{4}$

For$\frac{3\text{T}}{4}\le \text{t}\le \text{T}$,

i is zero$\therefore \frac{\text{di}}{\text{dt}}=0$

$\Rightarrow \text{e}=0$For$\frac{3\text{T}}{4}\le \text{t}\le \text{T}$

From this analysis, the variation of induced emf with time as shown in the figure below.