Assertion : The relative velocity of two photons travelling in opposite directions is C.
Reason : The rest mass of a photon is zero .

Options

A. If both the assertion and reason are true statement and reason is correct explanation of the assertion .
B. If both the assertion and reason are true statement but reason is not a correct explanation of the assertion .
C. If the assertion is true but the reason is a false statement.
D. If both assertion and reason are false statements.

Answer

B

Explanation

Very high velocities can not be added directly as in classical mechanics because this would lead to a violatio of the postulates of relatively . Such velocities are added in accordance with Lorentz transformations . It can be proved that any velocity added to the velocity of light gives velocity of light .
Relativistic mass of photon -
The relativistic momentum of photon is `p=(m_(0)V)/(sqrt(1-((v^(2))/(c^(2))))`
But `p=(h)/(lambda)`
` :. (h)/( lambda)=(m_(0)V)/(sqrt(1-((v^(2))/(c^(2))))`
`m_(0)=(h)/(v lambda)sqrt(1-((v^(2))/(c^(2)))`
For a photon v=c , then , `m_(0)=0`