### 2.2 The Concept of Metal

Let us have another look to the redistribution of charges when an accumulation of charge takes place inside the cube. Run the following simulation,  and let some time to be elapsed until a steady state is reached.

Two relevant facts are to be noticed:

• No charge remains inside the cube; all charges distribute over the surface.
• The force acting upon the charges is directed normal to the surface.
Moreover, it might be verified that:
• The electric field inside the metal is practically zero.
• The electric field is higher near zones of high curvature of the surface, outside the metal. Charge tends to accumulate near those zones.
In order to confirm the vanishing of the field inside the metal, a random distribution (in position and velocity) of charges is considered in the following simulation. A test charge (with value 1/1000 of the other charges) is also introduced, and we keep track of the force acting on it as a function of time.

It can be observed how the force goes to zero at the steady state.