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An electron of mass m and electric charge e is accelerated by a potential difference of V and then it enters in a magnetic field B perpendicular to the magnetic field lines. Radius of the circular path formed by electron is

Options

  1. A2 eV / m
  2. B2 Vm / eB 2
  3. C2 Vm / eB
  4. D2 Vm / e 2 B

Correct answer

B. 2 Vm / eB 2

Step-by-step solution

Bev = mv 2 r or r = mv Be as mv = 2 mT ( T = KE ) . So r = 2 mT Be As the electron has been accelerated from rest through a potential difference of V volt, then T = eV ∴ r = 2 mVe B 2 e 2 = 2 mV B 2 e

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