Question

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.

Answer 1

ANSWER=3
1.magnetic force does not cause any change in kinetic energy or speed of the particle.
2.F=QVB=MV²/R
OR , QB=MV/R
OR MV=QBR
Q,B,R ARE CHARGE,MAGNETIC FIELD AND RADIUS RESPECTIVELY WHICH SEEMS TO BE CONSTANT
HENCE
MOMENTUM IS ALSO CONSTANT
HENCE THE ANSWER IS 3.

Answer 2

Answer:(1) Its momentum(mΔv) changes but its kinetic energy remains constant.

Explanation:

Its kinetic energy remains constant as the magnetic field does not affect it. However, it does puts force on the particle resulting in acceleration and thus change in velocity resulting in change in momentum.F = ma and a = Δv/t and Δp = mΔv