QJEEM21Ph3014: JEE Main 2021 Physics - Class 12 JEEM21Ph3014 Solution: A charge Q is moving distance in the magnetic field . Find the…

Question

Verified Solution • 2025–26 Session moderate

A charge Q is moving

\overrightarrow {dl}

distance in the magnetic field

\overrightarrow {B}

. Find the value of work done by

\overrightarrow {B}

.

Accepted Answer

We know,

\overrightarrow F = q\left( {\overrightarrow v \times \overrightarrow B } \right)

\therefore

\overrightarrow F \bot \overrightarrow v

and

\overrightarrow F \bot \overrightarrow B

Power (p)

= {{dw} \over {dt}}

= {{\overrightarrow F .\,\overrightarrow {dl} } \over {dt}}

= \overrightarrow F \,.\,{{\overrightarrow {dl} } \over {dt}}

= \overrightarrow F \,.\,\overrightarrow v

= Fv\cos \theta

= Fv\cos 90^\circ

= 0

As power supply by the field is zero so, total work done also zero.

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