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Most Important Selected Qs for JEE AdvancedPhysicsMagnetic Effects of Current

An electron is orbiting in a circular orbit of radius r under the influence of a constant strong magnetic field of strength B. Assuming that Bohr's postulate regarding the quantisation of angular momentum holds good for this electron, find (a) the allowed values of the radius ' r ' of the orbit. (Assume that the charge on the electron is -e and the mass of the electron is m.)

Correct answer

3

Step-by-step solution

For the electron, we can write, m dW dQ %= 1 4 100=25 %= evB or, mv _ ( T / 4) = 2 mg = _ R ^ 2 R (p₀+ 4 S r ) 4 r ^2 d r ...(i) Using the Bohr quantisation condition, mvr = 3 R ^2 2 = n ~m 2 f ~T 9 , n integer. or, v r= n 2 f T 4 ...(ii) (a) r ^2= K ₂ ~K ₁- K ₂ = 2 1 or, r = K ₁ ~K ₂ = 3 2 ^2 2 ₀ = P ₁ 8 + ^2 2 ₀ = P ₀+ 4 ~T 2 r a ₀ ...(iii)

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