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Does light have mass? If not how can it exert a force ?

Does light have mass? If not how can it exert a force ?

Grade:10

1 Answers

Aarti Gupta
askIITians Faculty 300 Points
9 years ago
Light coming to us actually consist of small packets or bundles of energy,which are known as quanta or photons.These photons are massless particles i.e they do not have mass.So we can say that light has no mass.
But photons possess momentum.Momentum of an object is given as,
p = mv
where,m = mass of object
and v = velocity of object.
Thus photons carry momentum,p
Now according to Newton’ second law of motion force is given as,
F = ma ,where a = accelaration
but,Fis also given as F = dp/dt,which is rate of change of momentum.
Now if we assume that a beam of light is hitting an object than ,it will definitely impart momentum to the object and we saw that change in momentum is being equal to the force.Thus,we can say that light beam will exert force on that object.

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