Question

The mass of an electron is $9.1\times {10}^{-31}kg$ . If its K.E. is $3.0\times {10}^{-25}J$ . Calculate its wavelength.

Answer 1

Given that,

The mass of an electron=m= $9.1\times {10}^{-31}kg$ .

K.E.=$3.0\times {10}^{-25}J$

The velocity of the electron is obtained from its kinetic energy.

$v=\sqrt{\frac{2K.E}{m}}=\sqrt{\frac{2\times 3.0\times {10}^{-25}}{9.1\times {10}^{-31}}}=812m/s$

The wavelength of electron is,

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

h=Plank's constant= $6.626\times {10}^{-34}$

$=\frac{6.626\times {10}^{-34}}{9.1\times {10}^{-31}812}$

$=8953\times {10}^{-10}m=8953{}^{0}A$.