Photon A has twice the energy of photon B.The ratio of the momentum of A to that of B is
A)4
B)2
C)1
D)1/2
E)1/4

Question

Quizplus · Accepted Answer

The momentum of a photon is given by $p = \frac{E}{c}$, where $E$ is the energy of the photon and $c$ is the speed of light. If photon A has twice the energy of photon B ($E_A = 2E_B$), then the momentum of A ($p_A$) is twice the momentum of B ($p_B$), because $p_A = \frac{2E_B}{c} = 2\left(\frac{E_B}{c}\right) = 2p_B$. Therefore, the ratio of the momentum of A to that of B is 2.

Photon a Has Twice the Energy of Photon B