Guest

How can light have momentum as it does not have mass and p=mv

How can light have momentum as it does not have mass and p=mv

Grade:10

1 Answers

Saurabh Kumar
askIITians Faculty 2400 Points
9 years ago
The theory of Special Relativity, proved in 1905 (or rather the 2nd paper of that year on the subject) gives an equation for the relativistic energy of a particle;

E2=(m0c2)2+p2c2

where m0 is the rest mass of the particle (0 in the case of a photon). Hence this reduces to E=pc. Einstein also introduced the concept of relativistic mass (and the related mass-energy equivalence) in the same paper; we can then write

mc2=pc

where m is the relativistic mass here, hence

m=p/c

In other words, a photon does have relativistic mass proportional to its momentum.

Think You Can Provide A Better Answer ?

ASK QUESTION

Get your questions answered by the expert for free