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Question: Answered & Verified by Expert
A particle of mass m moves in a circular orbit in a central potential field Ur=12kr2. If Bohr's quantization conditions are applied, radii of possible orbitals and energy levels vary with quantum number n as:
PhysicsAtomic PhysicsJEE MainJEE Main 2019 (12 Jan Shift 1)
Options:
  • A rnn2,En1n2
  • B rnn,Enn
  • C rnn,Enn
  • D rnn,En1n
Solution:
2669 Upvotes Verified Answer
The correct answer is: rnn,Enn
Fr=-dUdr=-kr

For circular motion

|Fr|=kr=mv2rkr2=mv2 ........(i)

Bohr's quantization mvr=nh2π ....(ii)

From (i) and (ii)

m2v2m=kr2

1mnh2πr2=kr2n2h24π2mk=r4

r=h24π2mk1/4 n1/2

rn

From equation (i) Un

KE=12mv2PE=12kr2

E=K+U=12mv2+12kr2=kr2n

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