Question

what is Heisenberg principle?

Answer 1

The Heisenberg uncertainty principle states that it is impossible to know simultaneously the exact position and momentum of a particle. That is, the more exactly the position is determined, the less known the momentum, and vice versa. This principle is not a statement about the limits of technology, but a fundamental limit on what can be known about a particle at any given moment. This uncertainty arises because the act of measuring affects the object being measured. The only way to measure the position of something is using light, but, on the sub-atomic scale, the interaction of the light with the object inevitably changes the object's position and its direction of travel.

Answer 2

According to the Heisenburg Uncertainity principle it is impossible to determine simultaneously the exact position and the exact momentum of of an electron with the absolute accuracy and certainity
Mathematically,
Δx × Δpx ≥ h/4π
Δx ×Δ(mv) ≥h/4π
Δx ×Δvx ≥h/4π
where,
Δx is uncertainity in position
Δvx is uncertainity in velocity
Δpx is uncertainity in momentum