Question

Absorption of energy by an atom of hydrogen in the ground state results in the ejection of electron with de-Broglie wavelength $\lambda =4.7\times {10}^{-10}$ m. calculate the velocity of ejected photon.

• A. $3.087\times {10}^8$
• B. $3.271\times {10}^{-8}$
• C. $1.55\times {10}^6$
• D. $1.55\times {10}^{-6}$

Answer 1

The correct option is C $1.55\times {10}^6$

Given, $\lambda =4.7\times {10}^{-10}$ m.
Here de-Broglie wavelength $\lambda =\frac{h}{mv}$
The velocity of ejected electron $\left(v\right)=\frac{h}{m\lambda }$
$=\frac{6.626\times {10}^{-34}}{9.1\times {10}^{-31}\times 4.7\times {10}^{-10}}$
$=0.15492\times {10}^{7}m{s}^{-1}$
$=1.5492\times {10}^{6}m{s}^{-1}$