A plane electromagnetic wave of frequency 35 MHz travels in free space along the X-direction. At a particular point (in space and time) E=9.6 jVm^-1.…
JEE Main 2024 — Physics Electromagnetism
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A plane electromagnetic wave of frequency 35MHz travels in free space along the X-direction. At a particular point (in space and time) E=9.6j^Vm−1. The value of magnetic field at this point is:
Official previous-year question
Held on 29 Jan 2024 · Verified 6 Jul 2026.
Options
A
3.2×10−8k^T
B
3.2×10−8i^
C
9.6j^T
D
9.6×10−8k^T
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Solution
At every instant, the ratio of the magnitude of the electric field to the magnitude of the magnetic field in an electromagnetic wave equals the speed of light.
Therefore, BE=c
⇒BE=3×108
⇒B=3×108E=3×1089.6
⇒B=3.2×10−8T
Now, direction of magnetic field can be calculated as
B^=v^×E^
=i^×j^=k^
So, B=3.2×10−8k^T
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