A particle of mass m carrying charge q is accelerated by a p.d. V. it enters perpendicularly a region of uniform magnetic field B and executes circular arc of radius R . The specific charge (q/m) is :

Options

A. `(2V)/(B^(2) R^(2))`
B. `(V)/(2BR)`
C. `(VB)/(2R)`
D. `(mV)/(BR)`

Answer

A

Explanation

We have `qV = (1)/(2) mv^(2)` . So, the specific charge
`(q)/(m) = (v^(2))/(2V) = (B^(2) q^(2)R^(2)//m^(2))/(2V)`
Since Bqv `= (mv^(2))/(R) ` Which gives `v = (BqR)/(m)` . Therefore
`(q)/(m) = (2V)/(B^(2)R^(2))`