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Question:

In an electromagnetic wave in free space the root mean square value of the electric field is Erms=6V/m. The peak value of the magnetic field is:

4.23×10⁻⁸T

2.83×10⁻⁸T

1.41×10⁻⁸T

0.70×10⁻⁸T

Solution:

The correct option is C
2.83×10⁻⁸T
Erms=6V/m
Erms=Erms√2=6√2V/m
Now,E=cB →B=E/c=6√2/3×10⁸=2.828×10⁻⁸T