QJEEM07Ph7f93: JEE Main 2007 Physics - Class 12 JEEM07Ph7f93 Solution: A charged particle with charge q enters a region of constant,…

Question

Verified Solution • 2025–26 Session moderate

A charged particle with charge

q

enters a region of constant, uniform and mutually orthogonal fields

\vec{E}

and

\vec{B}

with a velocity

\vec{v}

perpendicular to both

\vec{E}

and

\vec{B},

and comes out without any change in magnitude or direction of

\vec{v}

. Then

Accepted Answer

Here,

\vec{E}

and

\vec{B}

are perpendicular to each other and the velocity

\vec{v}

does not change; therefore

q E = q v B \Rightarrow v = \frac{E}{B}

Also,

| \frac{\vec{E} \times \vec{B}}{B^{2}} | = \frac{E B \sin θ}{B^{2}}

= \frac{E B \sin 90^{\circ}}{B^{2}} = \frac{E}{B} = | \vec{v} | = v

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