State and explain Heisenberg's uncertainty principle.

Answer

The exact position and momentum of a moving microscopic particle cannot be calculated precisely at the same moment of time. If `Deltax` is the error in the measurement of position of the particle and if `Deltap` is the error in the measurement of momentum of the particle, then:
`Deltax.Deltap ge h/(4pi)` or `Deltax.(mDeltav) ge h/(4pi)`
where, `Deltax`=uncertainty in position
`Deltap`=uncertainty in momentum
`h`=Plank's constant
`m` = mass of the particle
`Deltav`= uncertainty in velocity.