(a) An electron m

Given-

(a) For electron

Radius of the circle = 1 m

Magnetic field strength = 0.50 T

Now,

The radius of the circle is given by,

where,

m is the mass of a electron

v= velocity of the particle

B = magnetic force

q= charge on the particle = C

Speed of light is 3x10⁸ m/s²

Here, the speed of the electron moving along the circle is greater than the speed of light, so it is not reasonable.

(b) For a proton,

The radius of the circle is given by,

where,

m is the mass of a proton

v= velocity of the particle

B = magnetic force

q= charge on the particle = C