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Physics · PYQ NEET UG 2025
हिन्दीThe electric field in a plane electromagnetic wave is given by \( E_z = 60\cos(5x + 1.5 \times 10^9 t)\text{ V/m} \). Then expression for the corresponding magnetic field is (here subscripts denote the direction of the field) :
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Correct answer · Option A
\( B_y = 2 \times 10^{-7} \cos(5x + 1.5 \times 10^9 t)\text{ T} \)
Explanation
Using \( B_0 = \frac{E_0}{c} = \frac{60}{3 \times 10^8} = 2 \times 10^{-7}\text{ T} \). The direction of wave propagation is \( -x \), electric field is along \( z \), so magnetic field must be along \( y \). Thus \( B_y = 2 \times 10^{-7} \cos(5x + 1.5 \times 10^9 t)\text{ T} \).
