Question

a photon has a wavelength of 3.5 a0. calculate its mass. (planck's constant h = 6.626 x 10-34 js. velocity of light = 3 x 108 m/s) (2) 7

Answer 1

GIVEN;lamda = 3.5 angstrom = 3.5x 10^-10
velocity of light.=3 x 108 m/s

m = h/lamda*v ( from de-brogile's equation)

m = 6.626 x 10^-34/3.5 x10^-10 x 3 x 10^8

m = 6.626 x 10^-32/10.5

m = 0.6310 x 10^-32

m = 6.31x 10^-33 kg

Answer 2

Answer:

Mass of photon is 6.31 x 10⁻³³ Kg.

Explanation:

de-Broglie matter waves :

• The waves associated with material particle in motion are called matter Audi broglie waves and their wavelength is called de-Broglie wavelength
• Consider, a photon having mass m and wavelength λ. From de-Broglie hypothesis :

$λ = \frac{h}{p} = \frac{h}{mc}$

• where, p is momentum of photon and is given by p = mc.

Given that :

• wavelength, λ = 3.5 x 10⁻¹⁰ m
• Planck's constant, h = 6.626 x 10⁻³⁴ Js
• speed of light, c = 3 x 10⁸ m/sec

Solution :

• Let, the mass of the photon be m.
• From de-Broglie matter wave hypothesis :

$λ = \frac{h}{mc} \\ m = \frac{h}{λc} \\ m = \frac{6.626 \times{10}^{-34}}{3.5 \times {10}^{-10} \times 3 \times {10}^{8}} \\ m = 6.31 \times {10}^{ -33} kg$

• Hence, mass of the photon is 6.31 x 10⁻³³ Kg.