Examples of Uncertainty Principle
The more exact form of the uncertainty principle is
The constant “h-bar” has approximately the value So in SI units: 2m Dx Dv ³ 10 -34
Examples: (See March Table 17-1)
- electron: m ~ 10-31 Kg, Dx ~ 10 -10 m, Dv ~ 10 7 m/s Can predict position in future for time ~ Dx /Dv ~ 10 -17 s
- pin-head m ~ 10-5 Kg, Dx ~ 10 -4 m, Dv ~ 10 -25 m/s Can predict position in future for time ~ Dx /Dv ~ 10 21 s (greater than age of universe!)
?p ?x ³ (1/2) h/2p = (1/2) h