1)

A particle of mass M and positive charge Q, moving with a  constant velocity   u1=4ˆims1, enters a region of uniform static magnetic field normal to the x-y plane. The region of the magnetic field extends from x=0 to x=L for all values of y. After passing through this region , the particle emerges on the other side after 10 milliseconds with  a velocity   u2=2(3ˆi+ˆj)ms1. The correct statement(s) is (are)


A) the direction of the magnetic field is -z direction

B) the direction of the magnetic field is +z direction

C) the magnitude of the magnetic field is 50πM3Q

D) the magnitude of the magnetic field is 100πM3Q units

Answer:

Option A,C

Explanation:

 u= 4 ˆi : v  =2(3ˆi+ˆj) 

842021929_m5.JPG

According  to the figure , magnetic field should be in direction , or along -z direction

 Further ,   tanθ=vyvx=223=13

        θ=300orπ6

 = angle  of v with x-axis

 = angle rotated by the particle

  =Wt =(BQM)t

        B=πM6Qt

                             =50πMQ   units   9as t =10-3  second)