Electromagnetic...

A flat circular coil of $$n$$ turns, area $$A$$ and resistance $$R$$ is placed in a uniform magnetic field $$B$$. The plane of coil is initially perpendicular to $$B$$. When the coil is rotated through an angle of $${180}^{o}$$ about one of its diameter, a charge $${Q}_{1}$$ flows through the coil. When the same coil after being brought to its initial position, is rotated through an angle of $${360}^{o}$$ about the same axis a charge $${Q}_{2}$$ flows through it. Then $${Q}_{2}/{Q}_{1}$$

A rectangular loop of sides $$a$$ and $$b$$ is placed in $$x-y$$ plane. A uniform but time varying magnetic field of strength $$\vec { B } =20t\hat { i } +10{ t }^{ 2 }\hat { j } +50\hat { k } $$ is present in the region. The magnitude of induced emf in the loop at time $$t$$ is :

A square loop of side $$b$$ is rotated in a constant magnetic field $$B$$ at angular frequency $$\omega$$ as shown in figure. What is the emf induced in it?

In the figure shown, a uniform magnetic field $$\left| \vec { B }  \right| =0.5T$$ is perpendicular to the plane of circuit. The sliding rod of length $$l=0.25m$$ moves uniformly with constant speed $$v=4 m{s}^{-1}$$. If the resistance of the slides is $$2\Omega$$, then the current flowing through the sliding rod is :

In the figure magnetic field points into the plane of paper and the conducting rod of length $$l$$ is moving in this field such that the lowest point has a velocity $${v}_{1}$$ and the topmost point has the velocity $${v}_{2}({v}_{2}> {v}_{1})$$. The emf induced is given by :

Two parallel long straight conductors lie on a smooth plane surface. Two other parallel conductors rest on them at right angles so as to form a square of side $$a$$. A uniform magnetic field $$B$$ exists at right angles to the plane containing the conductors. Now conductors start moving outward with a constant velocity $${v}_{0}$$ at $$t=0$$. Then induced current in the loop at any time $$t$$ is  ($$\lambda$$ is resistance per unit length of the conductors) :

Two metallic rings of radius $$R$$ are rolling on a metallic rod. A magnetic field of magnitude $$B$$ is applied in the region. The magnitude of potential difference between points $$A$$ and $$C$$ on the two rings (as shown), will be :

A square loop of side $$a$$ and a straight long wire are placed in the same plane as shown in figure. The loop has a resistance $$R$$ and inductance $$L$$. The frame is turned through $${18}^{o}$$ about the axis $$OO'$$. What is the electric charge that flows through the loop?

A vertical ring of radius $$r$$ and resistance $$R$$ falls vertically. It is in contact with two vertical rails which are joined at the top. The rails are without friction and resistance. There is a horizontal uniform magnetic field of magnitude $$B$$ perpendicular to the plane of the ring and the rails. When the speed of the ring is $$v$$, the current in the top horizontal of the rail section is

A flip coil consists of $$N$$ turns of circular coils which lie in a uniform magnetic field. Plane of the coils is perpendicular to the magnetic field as shown in figure. The coil is connected to a current integrator which measures the total charge passing through it. The coil is turned through $${180}^{o}$$ about the diameter. The charge passing through the coil is