Three particles are moving perpendicular to a uniform magnetic field and travel on circular paths (see the drawing). They have the same mass and speed. List the particles in order of their charge magnitude, largest to smallest.

Radius of a charged particle is given by

r=mv / Bq

= k / q

where k = m v / B is a constant.

i. e. more is the magnitude of charge, less is the radius. (inversely proportional)

From the diagram r_3 > r_2 > r_1 (more the curvature, less is the radius)

(although drawing is not given i am assuming the above order, however, one can change the order as per the diagram. The concept used remains the same)

therefore, q_1 > q_2 > q_3.