# A metallic rod of length 'l' is tied to a string of length 21 and made to rotate with angular speed

Question:

A metallic rod of length 'l' is tied to a string of length 21 and made to rotate with angular speed $\omega$ on a horizontal table with one end of the string fixed. If there is a vertical magnetic field ' $\mathrm{B}$ ' in the region, the e.m.f. induced across the ends of the rod is :

1. $\frac{2 \mathrm{B \omega} \mathrm{l}^{2}}{2}$

2. $\frac{3 B \omega l^{2}}{2}$

3. $\frac{4 \mathrm{~B} \omega \mathrm{l}^{2}}{2}$

4. $\frac{5 \mathrm{~B} \omega \mathrm{l}^{2}}{2}$

Correct Option: , 4

Solution: