If the radius of the first Bohr orbit is x, then de-Broglie wavelength of the electron in the third orbit is nearly

Angular momentum is quantized, hencemvrnnh2πBy Bohr's theory a0=Bohr's radius = xrn=n2a0Z=9a01=9x∴      mv9x=3h2π∴           mv=h6πxBy de-Broglie's equation λ=hmv=hh/6πx=6πx