Question

Light wave travelling in air along $x$-direction is given by $E_y=540 \sin \pi \times 10^4(x-c t) Vm ^{-1}$. Then, the peak value of magnetic field of wave will be (Given $c =3 \times 10^8 ms ^{-1}$ )

• A. $18 \times 10^{-7} T$
• B. $54 \times 10^{-7} T$
• C. $54 \times 10^{-8} T$
• D. $18 \times 10^{-8} T$

Answer 1

Answer: (A)

$ E _{ y }=540 \sin \pi \times 10^4( x - ct ) Vm ^{-1} $
$ E _0=540 Vm ^{-1} $
$ B _0=\frac{ E _0}{ C }=\frac{540}{3 \times 10^8}=18 \times 10^{-7} T $