Given: The magnetic field of a chamber is
Magnetic force
where, the charge on the electron is
By substituting the given values in the above equation, we get,
Magnetic force on the electron is
Magnetic force provide centripetal force on the electron due to which the electron starts moving in circular path of radius
Centripetal force exerted on the electron is given as,
where, the mass of the electron is
For equilibrium, centripetal force exerted on electron is equal to magnetic force.
By substituting the given values in the above equation, we get,
Thus, the radius of circular orbit is