Question

Two photons having

• A. equal wavelengths have equal linear momenta
• B. equal energies have equal linear momenta
• C. equal frequencies have equal linear momenta
• D. equal linear momenta have equal wavelengths

Answer 1

Answer: (D)

The magnitude of momentum and de-Broglie wavelength are related as
$\lambda =\frac{h}{p}$
Therefore if linear momenta are same then wavelengths are equal but if wavelengths are same then only the magnitudes of momenta are same while direction might be different.