The ratio of energies of two photons is 1 : 2, then ratio of their momenta will be 

CONCEPT:

Photon:

• According to Einstein's quantum theory light propagates in the bundles (packets or quanta) of energy, each bundle is called a photon and possesses energy.

The energy of photon:

• The energy of each photon is given by

Where c = Speed of light, h = Plank's constant = 6.6 × 10–34 m²kg s^-1, ν = Frequency in Hz, λ  = Wavelength of light

The momentum of the photon:

• The relation between the energy and momentum of the photon is given by

CALCULATION:

Given - The ratio of energies of two photons (E1 : E2) = 1 ∶ 2

• The relation between the energy and momentum of the photon is given by

Here c = constant, therefore