A photon of `lambda=4400 Å` is passing through vacuum. What is the mass and momentum of the photon ?

Options

A. `5xx10^(-30)` kg and `1.5xx10^(-25)` kg m/s
B. `5xx10^(-36)` kg and `1.5xx10^(-27)` kg m/s
C. Zero, `1.5xx10^(-26)` kg m/s
D. `5xx10^(-36)` kg and `1.6xx10^(-40)` kg m/s

Answer

B

Explanation

In vacuum, all photon travels with the same velocity (c).
Momentum of the photon,
`p=h/lambda=(6.6xx10^(-34))/(440xx10^(-10))=(6.6xx10^(-34))/(4.4xx10^(-7))`
`=1.5xx10^(-27)` kg m/s
and mass (m) `=p/c=(1.5xx10^(-27))/(3xx10^(8))=5xx10^(-36)`kg