**CBSE NOTES CLASS 12 PHYSICS **

**CHAPTER 11 DUAL NATURE OF RADIATION AND MATTER**

**Heisenberg’s uncertainty principle**

It is not possible to measure both the position and momentum of an electron (or any other particle) at the same time exactly. There is always some uncertainty (Δx) in the specification of position and some uncertainty (Δp) in the specification of momentum. The product of Δx and Δp is of the order of $\frac{h}{2\pi}$ or,

$$\Delta x\Delta p\approx \frac{h}{2\pi}$$