Question

The insulation property of air breaks down at `E=3xx10^(6) "volt"//meter`. The maximum charge that can be given to a sphere of diameter `5m` is approximately (in coulombs)
A. `2xx10^(-2)`
B. `2xx10^(-3)`
C. `2xx10^(-4)`
D. `2xx10^(-5)`

Answer 1

Correct Answer - b
`E= 1/(4piepsilon_(0))xx(q)/(r^(2))= 9xx10^(9)xx(q)/(r^(2))`
`:. Q=(Exxr^(2))/(9xx10^(9))=(3xx10^(6)xx(2.5)^(2))/(9xx10^(6))= 2.0833xx10^(-3)`
`q` should be less than `2.0833xx10^(-3)`. In the given set of opotions `2xx10^(-3)` is the maximum charge which is smaller than `2.0833xx10^(-3)`