Physics · 2026
JEE Main · 5 April 2026, Shift 2 · Q36
A metal rod of length L rotates about one end at origin with a uniform angular velocity ω. The magnetic field radially falls off as B( r )=B_o e^-λ…
A metal rod of length $\displaystyle L$ rotates about one end at origin with a uniform angular velocity $\displaystyle \omega$. The magnetic field radially falls off as $\displaystyle B(\mathrm{r})=B_{\mathrm{o}} \mathrm{e}^{-\lambda r} ; \lambda$ being a positive constant. The emf induced (neglecting the centripetal force on electrons in the rod) is :
Official answer
From NTA’s final answer key for this paper.
(1)
$\displaystyle B_o \omega\left[\frac{1}{\lambda^2}-e^{-\lambda L}\left(\frac{1}{\lambda^2}+\frac{L}{\lambda}\right)\right]$
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JEE Main 2026 Physics question, with the answer from NTA’s final answer key. Where our answers come from.