The dimensional formula of the de Broglie wavelength is

The correct answer is Option (3) → \( [\mathrm{L}] \)

The de Broglie wavelength \( \lambda=h/p \) is a wavelength, that is, a length. Its dimensions follow from those of Planck’s constant \( h \) and momentum \( p \):

    \( \begin{aligned} [\lambda] &= \frac{[h]}{[p]} \\ &= \frac{[\mathrm{ML^{2}T^{-1}}]}{[\mathrm{MLT^{-1}}]} \\ &= [\mathrm{L}] \end{aligned} \)

Its SI unit is the metre.

NCERT (2026-27):
Summary