If the position of a particle is known absolutely, then the uncertainty in the momentum of the particle must be _____.
A) equal to its mass
B) equal to the Planck's constant
C) infinite
D) equal to the velocity of the particle
E) zero

Question

Quizplus · Accepted Answer

This statement is a direct application of Heisenberg's Uncertainty Principle which states that it is impossible to know both the exact position and exact momentum of a particle simultaneously. The uncertainty in momentum is inversely proportional to the uncertainty in position, so if the position is known absolutely (i.e. zero uncertainty), then the uncertainty in momentum would have to be infinite.

If the Position of a Particle Is Known Absolutely, Then