Question

1 point
24) Assertion: When a charged
particle enters in the direction
of a uniform magnetic field,
then it moves on a straight path
without deviation.
Reason:Magnetic force on a
charged particle is zero, when
it moves in the direction of
magnetic field. *​

Answer 1

Answer:

both the assertion and reason are correct and the reason is correct explanation of the assertion (not confirmed answer)

Answer 2

Both assertion and reason are correct.

• The magnetic force acting in a uniform magnetic field is given by,

        $F=q v\times B$

        where B = magnetic field

                    q =  charge of the particle

                    v = velocity of the particle

• Magnetic force is the vector product of the velocity and the magnetic field, hence, $F=qvBSin\theta$ where $\theta$ is the angle between the velocity and the magnetic field.
• Since the particle is moving in the direction of the magnetic field hence the angle between the velocity vector and magnetic field vector would be zero
• So, according to the formula of magnetic force, the magnetic force would be zero.

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