Electron and Photon have same de Broglie wavelength, which of the following is true for their momentum:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Momentum of electron = momentum of photon
The de Broglie relation links the wavelength of any particle, a material particle or a photon, to its momentum.
\( \displaystyle \lambda = \frac{h}{p} \;\Rightarrow\; p = \frac{h}{\lambda} \)
Since \( h \) is a universal constant, equal wavelengths mean equal momenta, whatever the mass of the particle.
NCERT (2026-27):
Wave Nature of Matter – “… De Broglie proposed that the wave length λ associated with a particle of momentum p is given as
\( \displaystyle \lambda = \frac{h}{p} = \frac{h}{m v} \qquad (11.5) \)
where m is the mass of the particle and v its speed. … That is, the de Broglie wavelength of a photon given by Eq. (11.5) equals the wavelength of electromagnetic radiation of which the photon is a quantum of energy and momentum.”