Question

Sodium burns violet in a flame. What is the energy of this blue light if a photon released has a wavelength of 413nm

Answer 1

According to Einstein the energy of photon is given by the equation,

E = hν = h . c/λ

where h is Planck's constant, c is the speed of light, ν is the frequency of light and λ is the wavelength of light.

Given, wavelength of photon = 413 nm = 413 x 10⁻⁹ m

Conversion factor: 1 nm = 10⁻⁹ m

c = 3 x 10⁸ m/s

h = 6.626× 10⁻³⁴ J.s

Substituting the data into the equation we get,

E = h . c/λ

E = 6.626× 10⁻³⁴ J.s x (3 x 10⁸ m/s) / 413 x 10⁻⁹ m

E = 4.8 x 10⁻¹⁹ J

The energy of this blue light is  4.8 x 10⁻¹⁹ J