Q115 / 120 · VITEEE 2012 · Physics

The current $\mathrm{i}$ in a coil varies with time as shown in the figure. The variation of induced emfwith time would be Figure

  • A
    Figure
  • B
    Figure
  • C
    Figure
  • Correct answer
    D
    Figure

Solution

We know, inducedemf $$ \mathrm{e}=-\mathrm{L} \frac{\mathrm{di}}{\mathrm{dt}} $$ During 0 to $\frac{\mathrm{T}}{4}, \frac{\mathrm{di}}{\mathrm{dt}}=$ constant $\mathrm{So}, \mathrm{e}=-\mathrm{ve}$ For $\frac{T}{4}$ to $\frac{T}{2}, \frac{d i}{d t}=0$ i.e., $\mathrm{e}=0$ For $\frac{T}{4}$ to $\frac{3 \mathrm{~T}}{4}, \frac{\mathrm{di}}{\mathrm{dt}}=$ constant i.e., $\mathrm{e}=+\mathrm{ve}$

Hence, the correct answer is option: 'D'.

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