Question

The amplitude of the sinusoidially oscillating electric field of a plane wave is $ 60\, V/m $ . Then the amplitude of magnetic field is:

• A. $ 2\times {{10}^{2}}T $
• B. $ 6\times {{10}^{7}}T $
• C. $ 6\times {{10}^{2}}T $
• D. $ 2\times {{10}^{-7}}T $
• E. $ 3\times {{10}^{8}}T $

Answer 1

Answer: (D)

The instantaneous magnitudes of electric field (E) and magnetic field (B) are related as
$ \frac{E}{B}=c $ $ \Rightarrow $ $ B=\frac{E}{c} $
Given, $ E=60\,V/m,c=3\times {{10}^{8}}m/s $
$ \therefore $ $ B=\frac{60}{3\times {{10}^{8}}}=2\times {{10}^{-7}}T $