Why light have momentum even if photons are massless This is because momentum is a property by which an object can influence other object’s motion, and light can do that so it has momentum Another reason for this is even if light has zero rest mass but it does have an energy and this energy will also correspond to an equivalent mass, this mass works as momentum There is a lot of confusion in people’s mind regarding momentum because: It is generally taught that P=mv Where, P = momentum, m = mass and v = velocity of an object This formula is not completely wrong, but it's not completely correct as well, because it's incomplete In the complete formula for momentum: Momentum not only depends on the mass of an object, but also on the total energy of that object In other words, there are 2 things which are responsible for the momentum of an object: 1- It's mass 2- Its energy This means that even if the mass of an object is