Question

The ratio of the energy required to set up in cube of side 10 cm uniform magnetic field of 4${Wb/m}^2$ and a uniform electric field of ${10}^{6}V/m$ is:

• A. $1.4x{10}^7$
• B. $1.4x{10}^5$
• C. $1.4x{10}^6$
• D. $1.4x{10}^3$

Answer 1

The correct option is A $1.4x{10}^7$

Side $=10cm$

magnetic field $=4wb/m^2$

electric field $={10}^{6}V/m$

$B=E\times r$

or, $\frac{E_1}{E_2}=\frac{\frac{1}{2}\times B^2}{\frac{1}{2}\times E^2}$

or, $\frac{E_1}{E_2}=\frac{5.6\times {10}^6\times 10}{4}$

$=\frac{5.6\times {10}^7}{4}$

$=1.4x{10}^7$