Q 12-06-074JEE MainJEE Main 2023 (15 Apr, Shift 1)Easy
A $20\ \text{cm}$ long metallic rod is rotated with $210$ rpm about an axis normal to the rod passing through its one end. The other end of the rod is in contact with a circular metallic ring. A constant and uniform magnetic field $0.2\ \text{T}$ parallel to the axis exists everywhere. The emf developed between the centre and the ring is ______ mV. (Take $\pi=\frac{22}{7}$)
Numerical value type. Enter your answer.
Answer: 88
$\omega=2\pi\times\dfrac{210}{60}=7\pi=22\ \text{rad s}^{-1}$.
$$\varepsilon=\frac12B\omega L^2=\frac12\times0.2\times22\times0.04=0.088\ \text{V}=88\ \text{mV}$$
Solution by Sreeraj P, M.Sc Physics