According to Bohr's theory, the moment of momentum of an electron revolving in 4ᵗʰ orbit of hydrogen atom is:

Solution

Physics sir · 3 steps

Moment of momentum is just angular momentum, and Bohr fixes it at n times h/2π.

1. Name the quantity. Moment of momentum is another name for angular momentum, L = mvr. Bohr's second postulate says it can only take whole-number multiples of h/2π.

   L = mvr = nh/2π

2. Fourth orbit. For the 4th orbit, n = 4, so L = 4h/2π = 2h/π.
3. So. The angular momentum in the 4th orbit is 2h/π, which is option (a).

The idea to keep. In Bohr's model, angular momentum in the nth orbit is always nh/2π. It grows linearly with n and does not depend on Z.

Answer from the NTA final answer key. Solution by PrepWiser.