Question

The de Broglie wavelength of an electron in the first orbit of Bohr’s hydrogen atom is 

(1) πr 

(2) πr/2 

(3) 2πr

(4) 2πr/3

Answer 1

The de Broglie wavelength of an electron is given by

For first orbit, hence n =1 thus, 2πr = χ  

Hence, the correct option is (3).