Question

The relation $p=\frac{h}{\lambda }$ is valid for

• A. macroscopic particles
• B. quantum particles
• C. relativistic particles
• D. any particle

Answer 1

The correct option is B quantum particles

According to quantum mechanics particles possess dual nature hence, when it is moving with velocity equal to velocity of light, de-Broglie wavelength is associated with it.
Energy of the particle is
$E=h\nu$
where, h is plank's constant, $\nu$ is frequency.
But according to mass-energy relation
$E=m{c}^2$
where, m is mass of the particle and c is velocity of light.
$mc=\frac{E}{c}=\frac{h\nu }{c}$
$p=\frac{h}{\lambda }$
$\lambda$ is the de-Broglie wavelength of particle.
Hence, the momentum is associated with quantum particles.