A particle of mass $M$ and positive charge $Q$, moving with a constant velocity $\overrightarrow{ u }_1=4 \hat{ i } ms ^{-1}$, 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 $\overline{ u }_2=2(\sqrt{3} \hat{ i }+\hat{ j }) ms ^{-1}$. 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 $\frac{50 \pi M }{3 Q }$ units.

$(D)$ The magnitude of the magnetic field is $\frac{100 \pi M}{3 Q}$ units.

  • [IIT 2013]
  • A

    $(B,D)$

  • B

    $(B,C)$

  • C

    $(A,C)$

  • D

    $(A,D)$

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