CBSE 2026 · Region 3 · Set 1 · Q3 · 1 mark
A plane electromagnetic wave travels through a medium and the magnetic field associated with it is given by \[\mathrm{B}=5 \times 10^{-8} \sin \left(3 \times 10^{10} \mathrm{t}-150 \mathrm{x}\right) \mathrm{T} \] where x is in metres and t is in seconds. The velocity of the wave is :
Official answer
From CBSE’s own marking scheme for this paper.
(A)
$\displaystyle 2.0 \times 10^{8} \mathrm{~ms}^{-1}$
Electromagnetic WavesApplymcqmedium
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CBSE Class 12 Physics past-paper question from the 2026board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.