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

Question

Assertion: The relative velocity of two photons travelling in opposite direction is the velocity of light. Reason: The rest mass of a photon is zero. (A) If both Assertion and Reason are true and the Reason is a correct explanation of the Assertion (B) If both Assertion and Reason are true but Reason is not a correct explanation of the Assertion (C) If Assertion is true but the Reason is false (D) If both Assertion and Reason are false

Tardigrade Admin · Accepted Answer

As the rest mass of a photon is zero, it always moves with the speed of light. And as we know that no material body can ever travel with a speed more than the speed of light in vacuum. Now as the two photons move with speed c of light opposite to each other, their relative velocity is also c.

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

If both Assertion and Reason are true and the Reason is a correct explanation of the Assertion

If both Assertion and Reason are true but Reason is not a correct explanation of the Assertion

If Assertion is true but the Reason is false

If both Assertion and Reason are false

As the rest mass of a photon is zero, it always moves with the speed of light. And as we know that no material body can ever travel with a speed more than the speed of light in vacuum. Now as the two photons move with speed $c$ of light opposite to each other, their relative velocity is also $c$ .

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