Question

The wavelengths of a proton and a photon are same. Then :

• A. their velocities are same
• B. their momenta are equal
• C. their energies are same
• D. their speeds are same

Answer 1

Answer: (B)

For proton,

$\lambda =\frac{h}{mv}$

${\lambda }_1=\frac{h}{p}$

For photon,

$E=\frac{hc}{\lambda }$

${\lambda }_2=\frac{h}{E/c}$

& ${\lambda }_1={\lambda }_2$

So $p=\frac{E}{c}$