Two particles move at right angle to each other. Their de Broglie wavelengths are λ1 and λ2 respectively. The particles suffer perfectly inelastic collision. The de Broglie wavelength λ, of the final particle, is given by:

• A. \(\frac{1}{{{\lambda ^2}}} = \frac{1}{{\lambda _1^2}} + \frac{1}{{\lambda _2^2}}\)
• B. \(\lambda = \sqrt {{\lambda _1}{\lambda _2}}\)
• C. \(\lambda = \frac{{{\lambda _1} + {\lambda _2}}}{2}\)
• D. \(\frac{2}{\lambda } = \frac{1}{{{\lambda _1}}} + \frac{1}{{{\lambda _2}}}\)