JEE Advanced Practice Quiz

Question 1

A circular conducting loop of radius r and resistance R is placed in a uniform magnetic field B perpendicular to its plane. The field decreases uniformly to zero in time t. The total charge that flows through the loop during this interval is

Accepted Answer

πr^2B/R

Question 2

A metal rod of length l moves with constant velocity v on two parallel conducting rails in a uniform magnetic field B perpendicular to the plane of the rails. The motional emf across the rod is

Accepted Answer

Blv

Question 3

A square loop of side a and resistance R lies in the plane of the page. A long straight wire carrying current I is parallel to one side of the loop and at distance d from the nearer side. If current in the wire increases at rate dI/dt, the induced emf in the loop is

Accepted Answer

(μ0a/2π)(dI/dt) ln((d+a)/d)

Question 4

A rod of mass m and resistance R slides down without friction on two vertical conducting rails separated by distance l in a uniform horizontal magnetic field B perpendicular to the plane of the rails. After a long time, the terminal speed of the rod is

Accepted Answer

mgR/(B^2l^2)

Question 5

A rectangular loop of width a and height b moves with constant velocity v into a region of uniform magnetic field B directed perpendicular to the plane of the loop. At an instant when the loop is partially inside the field, the induced emf is

Accepted Answer

Bbv

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