# Potential barrier

Representation of a potential  V (x) . The potential has a rectangular potential barrier of width 2 a and height  V 0 at position  x = 0 .

A potential barrier , also a potential threshold or potential wall , is a spatial area in which a potential assumes a local maximum (Figure area II). A function is referred to as potential that assigns a potential energy to every point in space or every state in a phase space . Spatial areas that are located between potential barriers and in which the potential assumes a local minimum are called potential wells. Whether a system or a particle can overcome a potential barrier (change from area I to area III of the figure) depends on its energy , the height and the shape of the barrier.

A potential barrier can have different forms. For calculation and illustration purposes, the shape of a rectangular function consisting of two potential levels is often used.

The Coulomb Wall is an important potential barrier .

## meaning

A potential barrier has the consequence that a certain physical process (e.g. the flow of an electric current or a movement due to gravitational forces ) is prevented or hindered. It can be a particle in a gravitational potential or a charged particle in an electrical potential along a spatial axis  x .

In classical physics , an object must have more energy than the energy  V 0 at the maximum of the potential barrier in order to be able to overcome it. To roll as a mountain, a ball must more kinetic energy have is when its potential energy at the top of the mountain. In quantum mechanics , however, a particle with lower energy can also overcome a potential barrier, which is then referred to as tunneling .