The ratio of the energy required to set up in a cube of side 10 cm, a uniform field of 4 `Wb//m^(2)` and a uniform electric field of `10^(6) V//m` is

Options

A. `1.44xx10^(7)`
B. `1.44xx10^(-5)c`.
C. `1.44xx10^(6)`
D. `1.44xx10^(3)`

Answer

c

Explanation

`U_(E)=1/2 epsilon_(0)E^(2)xx `volume
`U_(B)=(B^(2))/(2mu_(0)) xx` volume
`:. (U_(B))/(U_(E))=(B/E)^(2) 1/(mu_(0)epsilon_(0))=(4/(10^(6)))^(2) (3xx10^(8))^(2)`
`=16/(10^(12)) xx9xx10^(16) = 144xx10^(4) =1.44xx10^(6)`