A coil having 100 turns is placed in the magnetic field of 1m wb. Find the average EMF induced if the coil is moved in 0.2 seconds from the given field to a field of 0.4m wb.

Correct option is B

​$$\textbf{Given:} \\[4pt]\bullet \text{Number of turns, } N = 100 \\[4pt]\bullet \text{Initial magnetic flux, } \phi_1 = 1\,\text{wb} \\[4pt]\bullet \text{Final magnetic flux, } \phi_2 = 0.4\,\text{wb} \\[4pt]\bullet \text{Time, } t = 0.2\,\text{s} \\[8pt]\text{The formula for the induced EMF is given by:} \\[4pt]E = N \times \dfrac{\Delta \phi}{\Delta t} \\[8pt]\text{Where:} \\[4pt]\bullet N = \text{number of turns} \\[4pt]\bullet \Delta \phi = \text{change in flux } (\phi_2 - \phi_1) \\[4pt]\bullet \Delta t = \text{time interval} \\[8pt]E = 100 \times \dfrac{(0.4 - 1)}{(0.2 - 0)} \times 10^{-3} \\[8pt]E = 100 \times \dfrac{(-0.6)}{0.2} \times 10^{-3} \\[8pt]E = 100 \times (-3) \times 10^{-3} \\[8pt]E = -300 \times 10^{-3}\,\text{volts} \\[8pt]E = -0.3\,\text{volts} \\[8pt]\text{Since EMF is considered as an absolute value, the average EMF induced is: } E = 0.3\,\text{volts.}$$​​