Case : Read the passage and answer the question(s).

A charged particle whose mass is 19.9 ×10^-27 kg and charge is 1.6×10^-19 C moves with a speed of 3×10⁵ m/s at right angle to a magnetic field of 0.75 T.

In case of motion of a charged particle in a steady magnetic field, which of the following remain constant?

Speed

Since the direction of magnetic force will always be perpendicular to velocity, no work is done on the particle and so speed remains same, it only changes the direction.