A Van de Graaff generator has a spherical metal shell as an electrode which is at a potential `15 xx 10^(6)V`. If the dielectric strength of the surrounding medium is `5 xx 10^(7) Vm^(-1)`, then the diameter of the shell is

Options

A. 30 cm
B. 15 cm
C. 60 cm
D. 120 cm

Answer

C

Explanation

Potential difference, `V = 15 xx 10^(6)V`
Dielectric strength of medium `=5 xx 10^(7) V//m`
Electric field intensity,
`E = 5 xx 10^(7) V//m`
Minimum radius of spherical shell required for the purpose is given by
`r = (V)/( E) = (15 xx 10^(6))/(5 xx 10^(7)) = 0.3m`
Hence diameter, `d = 2r = 0.6m = 60cm`