Question

A magnetic flux of 500 $\mu$ Wb passing through a 200 turns coil. is reversed in $20\times {10}^{-3}$ seconds. The average emf induced in the coil in volts, is:

• A. 2.5
• B. 5.0
• C. 7.5
• D. 10.0

Answer 1

Answer: (D)

The induced emf in the coil is $e=-N\left(\frac{d\text{o }|}{dt}\right)$ Given $d\text{o }|\text{ =}\text{o}{|}_2-\text{o}{|}_1=2\times 500\mu Wb$ $dt=20\times {10}^{-3}\sec$ $N=200$ $e=-N\left(\frac{\text{o}{|}_2-\text{o}{|}_1}{dt}\right)$ Putting the given values in Eq. (i) $e=-\frac{200\times 2\times 500\times {10}^{-6}}{20\times {10}^{-3}}$ $=-10\text{volt }$ $\Rightarrow$ $|e|=10\text{volt}$