What will be momentum of a photon of wavelength 1000 Å? given h = 6.626 × 10-34 Js

CONCEPT:

• Photon: The photon is an elementary particle. It is a basic unit of light. 
  • Photons are massless, and they always move at the speed of light in a vacuum ( c = 3 × 108  m/s)
• The momentum of a photon: It is given by Planck's constant divided by the wavelength of the light.

\(P=\frac{h}{λ}\)

where P is the momentum of one photon, h is the Planck constant, and λ is the photon's wavelength. In this equation h is constants.

CALCULATION:

Given that: λ = 1000 Å = 1000 × 10-10 m

h = 6.626 × 10-34  (constant)

c =  3 × 108   (constant)

 p = h / λ 

⇒ p = 6.626 × 10-34 / 1000 × 10-10

⇒ p = 6.626 × 10-27 Kg-m/s

The correct answer is Option 1 i.e 6.626 × 10-27 Kg-m/s

Additional Information

• ​Despite photons having no mass, Photon particles carry momentum as well as energy.
  • There has been evidence that EM radiation carries momentum. (Maxwell and others who studied electromagnetic waves have predicted that these carry momentum.) 

• It is now a well-established fact that photons do have momentum and energy.

• Photon energy is the energy that is carried by a single photon. The amount of this energy is inversely proportional to the wavelength.