In a chamber, a uniform magnetic field of 6.5 G (1 G = T) is maintained. An electron is shot into the field with a speed of normal to the field. Explain why the path of the electron is a circle. Determine the radius of the circular orbit.

Magnetic field strength (B) = 6.5 G =

Speed of the electron (v) = 

Charge on the electron (e) = 

Mass of the electron (m_e) = 

Angle formed by the fired electron and the magnetic field, 

The magnetic force exerted on the electron in a magnetic field is given by the relationship:

The travelling electron receives centripetal force from this force. As a result, the electron begins to move in a circular route of radius r.

Hence, centripetal force exerted on the electron,

The centripetal force imparted on the electron is equal to the magnetic force at equilibrium, i.e.,

F_e = F

So,

As a result, the radius of the electron’s circular orbit is 4.2 cm.