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A charged particle is moved along a magnetic field line. The magnetic force on the particle is - Physics

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Question

A charged particle is moved along a magnetic field line. The magnetic force on the particle is 

Options

  • along its velocity

  •  opposite to its velocity

  • perpendicular to its velocity

  • zero

MCQ

Solution

zero 

The force on a charged particle q moving with velocity v in a magnetic field B is given by

\[\vec{F} = q( \vec{v} \times \vec{B} )\] 
As the charge is moving along the magnetic line of force, the velocity and magnetic field vectors will point in the same direction, making a cross product.

\[( \vec{v}  \times  \vec{B} )   =   0\] 

\[ \Rightarrow  \vec{F}    =   0\]

So, the magnetic force on the particle will be zero.
 
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Chapter 13: Magnetic Field due to a Current - MCQ [Page 248]

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HC Verma Concepts of Physics Vol. 2 [English] Class 11 and 12
Chapter 13 Magnetic Field due to a Current
MCQ | Q 6 | Page 248

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