Question

Two spheres are isolated from each other. They each have an identical net positive charge and the same radius. One sphere is solid and insulating while the other is a hollow conducting sphere whose charge is uniformly distributed.
For which sphere is the electric field the greatest at a distance x from the center of the spheres? Assume x is greater than the radius of the spheres.

• A. The conducting hollow sphere has a greater E-field.
• B. The insulating solid sphere has a greater E field.
• C. Both spheres have the same E field.
• D. Neither sphere would cause there to be an Electric field.

Answer 1

Answer: (C)

Both spheres have the same E field.

Electric field $E$ due to a conducting spherical shell of radius $r$ , having a charge $q$ , at a distance $x$ is given by ,

$E=kq/x^2$ (where $x>r$)

Electric field $E$ due to a insulating solid sphere of radius $r$ , having a charge $q$ , at a distance $x$ is given by ,

$E=kq/x^2$ (where $x>r$)

we can see that both the fields are same .