Question:
The speed of electrons in a scanning electron microscope is $1 \times 10^{7} \mathrm{~ms}^{-1}$. If the protons having the same speed are used instead of electrons, then the resolving power of scanning proton microscope will be changed by a factor of:
Correct Option: 1
Solution:
Resolving power $(\mathrm{RP}) \propto \frac{1}{\lambda}$
$\lambda=\frac{\mathrm{h}}{\mathrm{P}}=\frac{\mathrm{h}}{\mathrm{mv}}$
So $(\mathrm{RP}) \propto \frac{\mathrm{mv}}{\mathrm{h}}$
$R P \propto P$
$\mathrm{RP} \propto \mathrm{mv}$
$\mathrm{RP} \propto \mathrm{m}$