Question

Solve previous year Question of iit jee
chapter :- magnetic effect of current​

Answer 1

Answer:

A particle of mass M and charge Q with velocity V describes circular path of radius R with magnetic field B.

So, F = Q(V×B)

Since, the path is circular the tangent of the circle will give the velocity.

And the force will be perpendicular to the velocity and displacement.

Work done , W = F•s

= Fscos90°

= 0

Hence, The work done by the partice is zero.

Answer 2

Answer:

option (b)

Explanation:

Given :- mass "M"

• charge "Q"
• velocity"V"
• Magnetic field "B"

when particle describe circular path in a magnetic field, its velocity is always perpendicular to the magnetic force .

• Power, P = f.vcosθ

P = f.vcosθ Hence, θ = 90°

• ∴ P = 0

But , P = W/t

• → P = W/t → W = P•t

Hence,work done , W = 0 [Everywhere]