High School Physics

No charge on the inner surface of the hollow object when charged – why?

Last updated on March 29th, 2022 at 06:52 pm

When a hollow conducting object is charged, either negatively or positively, does the charge distribute evenly throughout the inner and outer surfaces of the object?

It is witnessed that, excess charges move to achieve static equilibrium, and they move as far apart as possible because of electrostatic forces of repulsion. In a hollow conducting object, all excess charges are still repelled outward, as shown in Figure 1(a).

However, they distribute evenly only on the outer surface of the conducting object. There is no excess charge on the inner surface of the hollow object, no matter what the shape of the object is.

The corresponding electric field lines created by the distribution of charge on the outer surface of a hollow object are shown in Figure 1(b).

Figure 1(a) - a charged hollow conducting object - all charges are on the outer surface only. 
Figure 1(b) - electric field lines on a hollow conducting object are shown
figure 1(a) and 1(b)

The electric field lines at the outer surface must always be perpendicular to the outer surface.

See also  Equipotential lines & surfaces in an electric field
Scroll to top