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Physics - Modern Physics Question with Solution | TestHub

PhysicsModern PhysicsDe Broglie & Matter WavesHard2 minPYQ_2019

PhysicsHardsingle choice

Assertion: The relative velocity of two photons travelling in opposite direction is the velocity of light. Reason : The rest mass of photon is zero.

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Answer:

Solution:

Velocity of first photon $= u = c$ Velocity of second photon $= v = - c$ Now, relative velocity of first photon with respect to second photon $= \frac{u - v}{1 - \frac{uv}{c ^{2}}} = \frac{c - ( - c )}{1 - \frac{( c ) ( - c )}{c ^{2}}} = \frac{2 c}{1 + \frac{c ^{2}}{c ^{2}}} = \frac{2 c}{1 + 1} = \frac{2 c}{2} = c$ Also the rest mass of photon is zero.

Stream:AIIMSSubject:PhysicsTopic:Modern PhysicsSubtopic:De Broglie & Matter Waves

⏱ 2mℹ️ Source: PYQ_2019

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