A uniformly charged spherical conductor has a radius of 1m and surface charge density 0.8Cm2. The electric field magnitude because of this at a point 1m radially away, from the surface of the sphere is
2.25×1010NC
While calculating electric field at any outside point (outside the surface I mean), a sphere behaves like a point charge and the electric field magnitude is given by
Here it is given σ=0.8Cm2
As Q=σ×area
=σ×4πR2
We have Q=0.8×4π×12
≈10C
Remember that the ‘r’ in the equation of electric field is the distance from the centre of the sphere and not from its surface.
So here r = R + distance from surface
= 1m + 1m (given)
=2m
∴|→E|=9×109×10C22=2.25×1010NC