If the acceleration and velocity of a charged particle moving in a constnt magnetic region is given by `a=a_1hati+a_2hatk, v=b_1hati+b_2hatk.[a_1,a_2,b_1` and `b_2` are constant]. Then choose the wrong statement

Options

A. magnetic field may be along y-axis
B. `a_1b_1+a_2b_2=0`
C. magnetic field is along x-axis
D. kinetic energy of particle is always constant

Answer

C

Explanation

a. `B_|_v`, so it may along `y`- axis
b. `F_|_v`,
`:. a_|_v=0`
or `a.v=0`
or `a_1b_1=a_2b_2`
c. See the logic of option a.
d. Magnetic force cannot change the kinetic energy of a particle.