Potential Barrier

A potential barrier is like an energy obstacle that particles, such as electrons, need to overcome to move from one place to another. Imagine rolling a ball up a hill; it requires energy to climb the hill. In physics, if the barrier is high enough relative to the particle's energy, the particle might not cross it easily. However, in quantum mechanics, there's a chance it can "tunnel" through the barrier even if it doesn't have enough energy to climb over it. This concept explains phenomena like electron flow in semiconductors and nuclear fusion.