Question

What is the mass of a particle with a Wavelength of $3.313\mathring{A}$ moving with a speed of $2.0\times 10^{8}m{s}^{-1}$ ?

• A. $1.0\times 10^{-28}kg$
• B. $2.0\times 10^{-32}kg$
• C. $1.0\times 10^{-32}kg$
• D. $2.0\times 10^{-28}kg$

Answer 1

Answer: (C)

According to de-Broglie relation:

$\lambda =\frac{h}{mv}$

where, $h=$ Planck's constant $=6.626\times 10^{-34}Js$

$v=$ speed of moving particle

$m=$ mass of moving particle

$\lambda =$ wavelength of particle.

Thus,

$m-\frac{h}{\lambda \times v}$

Given,

Speed (velocity) of moving particle $(v)=2\times 10^{8}m/s$

Wavelength of moving particle $(\lambda )=3.313\mathring{A}$

$=30313\times 10^{-10}m$

$\therefore m=\frac{6.626\times 10^{-34}}{3.313\times 2\times 10^8\times 10^{-10}}$

$m=1\times 10^{-32}kg$