Question

The value of the electric field strength in vacuum if the energy density is same as that due to a magnetic field of induction $1$ $T$ in vacuum is

• A. $3\times {10}^{8}N$ $C^{-1}$
• B. $1.5\times {10}^{8}N$ $C^{-1}$
• C. $2.0\times {10}^{8}N$ $C^{-1}$
• D. $1.0\times {10}^{8}N$ $C^{-1}$

Answer 1

The correct option is A $3\times {10}^{8}N$ $C^{-1}$

$\frac{1}{2}{\epsilon }_0{E}^2=\frac{1}{2{\mu }_0}{B}^2$

$E=\sqrt{\frac{B^2}{{\mu }_0{\epsilon }_0}}$

velocity of light $c=\sqrt{\frac{1}{{\mu }_0{\epsilon }_0}}=3\times {10}^8$

=$B=3\times {10}^{8}N{C}^{-1}$