Physics · 2025
JEE Main · 23 January 2025, Shift 1 · Q39
The electric field of an electromagnetic wave in free space is E =57 cos [7.5 × 10^6 t -5 × 10^-3(3 x+4 y)](4 i -3 j ) N / C. The associated magnetic…
The electric field of an electromagnetic wave in free space is
$$\overrightarrow{\mathrm{E}}=57 \cos \left[7.5 \times 10^6 \mathrm{t}-5 \times 10^{-3}(3 x+4 y)\right](4 \hat{i}-3 \hat{j}) N / C .
$$
The associated magnetic field in Tesla is
Official answer
From NTA’s final answer key for this paper.
(4)
$\displaystyle \overrightarrow{\mathrm{B}}=-\frac{57}{3 \times 10^8} \cos \left[7.5 \times 10^6 \mathrm{t}-5 \times 10^{-3}(3 x+4 y)\right](5 \hat{k})$
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JEE Main 2025 Physics question, with the answer from NTA’s final answer key. Where our answers come from.