Question

Find the velocity of an electron so that its momentum is equal to the photon of wavelength 5200 $Å$ ?

• A. $700 \, ms^{- 1}$
• B. $1000 \, ms^{- 1}$
• C. $1400 \, ms^{- 1}$
• D. $2800 \, ms^{- 1}$

Answer 1

Answer: (C)

According to De Broglie's equation Momentum,
$p = \frac{h}{\lambda }$
or $v=\frac{h}{m \lambda }=\frac{6.62 \times 10^{- 34}}{9.1 \times 10^{- 31} \times 5.2 \times 10^{- 7}}$
$=1.4\times 10^{3} \, ms^{- 1}=1400 \, ms^{- 1}$