question_answer

A charged particle moves through a magnetic field in a direction perpendicular to it.                             [AIPMT 2003]

A)  acceleration remains unchanged  

B)       velocity remains unchanged

C)              speed of the particle remains unchanged

D)              direction of the particle remains unchanged Correct Answer: C Solution : [c] When a charged particle moves through a perpendicular magnetic field, then a magnetic force acts on it which changes the direction of particle but does not alter the magnitude of its velocity (i.e. speed).

Note:    If a charged particle moves at \[{{45}^{o}}\] to magnetic field then path of the particle will be a helix whose circular part has radius according to relation \[r=\frac{mv\,\sin \theta }{qB}\].