Question

The mass of an electron is $9.1\times {10}^{-28}$ g and the uncertainty in velocity is equal to $2\times {10}^{-3}cm/sec$. The uncertainty in the position of an electron is:

[$h=6.62\times {10}^{-27}$ erg sec]

• A. $2.9\times {10}^{2}cm$
• B. $2.9\times {10}^{-2}cm$
• C. $2.9\times {10}^{-12}cm$
• D. None of these

Answer 1

The correct option is A $2.9\times {10}^{2}cm$

Using the formula: $\Delta x\times \Delta p=\frac{h}{4\pi }$.

Now, $\Delta p=m\Delta v=9.1\times {10}^{-28}gm\times 2\times {10}^{-3}cm/sec=1.82\times {10}^{-30}gmcm/sec=1.82\times {10}^{-35}kgm/sec$

Therefore, $\Delta x=\frac{h}{4\pi \Delta p}=2.9m=2.9\times {10}^{2}cm$.