Q.

A small particle of mass m moves in such a way that its potential energy U=12mω2r2 where ω is constant and r is the distance of the particle from origin. Assuming Bohr's quantization of momentum and circular orbit, the radius of nth orbit will be proportional to.               [2023]

1 n  
2 n  
3 n2  
4 1n  

Ans.

(1)

U=12mω2r2

F=-dUdr=-mω2r

Now  mω2r=mv2r  v=ωr    (i)

and  mvr=nh2π    (ii)

From (i) and (ii),

mωr2=nh2π  rn