At t = 0 , a positively charged particle of mass m is projected from origin with velocity u_0 at an

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4.Moving Charges and Magnetism

hard

At $t$ = $0$, a positively charged particle of mass $m$ is projected from the origin with velocity $u_0$ at an angle $37^o $ from the $x-$axis as shown in the figure. A constant magnetic field ${\vec B_0} = {B_0}\hat j$ is present in space. After a time interval $t_0$ velocity of particle may be:-

A

${u_0}\left[ {\frac{{\sqrt {39} }}{2}\hat i + \frac{3}{5}\hat j - \frac{{\hat k}}{{\sqrt 3 }}} \right]$

B

${u_0}\left[ {\frac{{\hat i}}{{\sqrt 3 }} + \frac{{\hat j}}{{\sqrt 2 }} + \frac{{\hat k}}{{\sqrt 6 }}} \right]$

C

${u_0}\left[ {\frac{{\sqrt {39} }}{{10}}\hat i + \frac{3}{5}\hat j + \frac{1}{4}\hat k} \right]$

D

${u_0}\left[ {\frac{{\sqrt {39} }}{{10}}\hat i + \frac{3}{5}\hat j + \frac{1}{2}\hat k} \right]$

Solution

At any instant $|v|$ = $v_0$ $\&$ component along $y$-axis must remain constant

Standard 12

Physics

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