If a charged particle moves through a region of magnetic field pointing in the direction perpendicular to its direction of velocity. Then during its subsequent motion, (1) Its momentum changes but the kinetic energy remains constant (2) Its momentum and kinetic energy both changes. (3) Its momentum and kinetic energy both remains constant. (4) Its kinetic energy changes but the momentum remains constant.



(3) It's momentum and kinetic energy remains constant as the angle here is 90 degree
But when I search in my book it says momentum changes