Question

If the electron has same momentum as that of a photon of wavelength 5200Å, then the velocity of electron in m /sec is given by

• A. 10³
• B. 1.4 × 10³
• C. 7 × 10^–5
• D. 7.2 × 10⁶

Answer 1

Answer: (B)

1.4 × 10³

Answer 2

$\lambda = \frac{h}{mv}$ ⇒ $v = \frac{h}{m\lambda} = \frac{6.6 \times 10^{- 34}}{9.1 \times 10^{- 31} \times 5200 \times 10^{- 10}}$

⇒ v = 1.4 × 10³ m/s.