Two identical -ray photons each strike free electrons that are initially at rest

PHYSICS · Single correct · CBSE · Physics · Dual Nature of Radiation and Matter · Dual Nature of Radiation and Matter

Problem

Two identical

\gamma

-ray photons each strike free electrons that are initially at rest. For photon A the scattering angle of the photon is

15^{\circ}

, while for photon B it is

135^{\circ}

. Which of the following statements best describes the kinetic energies

K_A

and

K_B

of the recoil electrons? (a)

K_A = K_B

because the incident photons have the same energy. (b)

K_A > K_B

because a smaller scattering angle corresponds to greater momentum transfer to the electron. (c)

K_A < K_B

because a larger scattering angle corresponds to a larger wavelength increase of the photon. (d)

K_A

\, and

K_B

cannot be compared without knowing the initial photon wavelength.