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A small sphere carries a charge of 20muC...

A small sphere carries a charge of `20muC`. The energy density of electric field at a point 25 cm away from the centre of the sphere in air is

A

`0.367J//m^(3)`

B

`3.67J//m^(3)`

C

`36.7J//m^(3)`

D

`3.76J//m^(3)`

Text Solution

Verified by Experts

The correct Answer is:
C
`E=1/(4piin_(0)k)q/r^(2)=(9xx10^(9)xx20xx10^(-6))/(1xx625xx10^(-4))`
`=0.288xx10^(7)N//C`
`therefore" " u=1/2in_(0)kE^(2)`
`=(8.85xx10^(-12)xx1xx(0.288xx10^(7))^(2))/2`
`=36.7J//m^(3)`
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