Question bank/NEET UG/Physics

NEET UGPhysicsModerateNEET 2025

The electric field in a plane electromagnetic wave is given by
Ez=60cos⁡(5x+1.5×109t)E_z = 60 \cos (5x + 1.5 \times 10^9 t) V/m.
Then expression for the corresponding magnetic field is (here subscripts denote the direction of the field) :

Show answer and solution
In electromagnetic wave, EE and BB are in same phase and B0=E0cB_0 = \frac{E_0}{c}; their planes are perpendicular to each other.
∴By=60ccos⁡(5x+1.5×109t)\therefore B_y = \frac{60}{c} \cos(5x + 1.5 \times 10^9 t) T
=603×108cos⁡(5x+1.5×109t)= \frac{60}{3 \times 10^8} \cos(5x + 1.5 \times 10^9 t) T
By=2×10−7cos⁡(5x+1.5×109t)B_y = 2 \times 10^{-7} \cos(5x + 1.5 \times 10^9 t) T

Source: geekyrakshit/indian-exam-questions / neet2025-code45

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