EASY
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A uniform but time-varying magnetic field B(t) exists in a circular region of radius a and is directed into the plane of the paper as shown. The magnitude of the induced electric field at point P (outside the circular region) at a distance r from the centre of the circular region

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Important Questions on Electromagnetic Induction

HARD

An infinitely long straight wire carrying current I, one side opened rectangular loop and a conductor C with a sliding connector are located in the same plane, as shown in the figure. The connector has length l and resistance R. It slides to the right with a velocity v. The resistance of the conductor and the self-inductance of the loop are negligible. The induced current in the loop, as a function of separation r, between the connector and the straight wire is:

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HARD

A square-shaped conducting wire loop of dimension a moving parallel to the x-axis approaches a square region of size b(a<b) where a uniform magnetic field B exists pointing into the plane of the paper (see figure). As the loop passes through this region, the plot correctly depicting its speed (v) as a function of x is.

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MEDIUM
A conducting bar of mass m and length l moves on two frictionless parallel rails in the presence of a constant uniform magnetic field of magnitude B directed into the page as shown in the figure.The bar is given an initial velocity v0 towards the right at t=0.
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Then, the
MEDIUM
A thin diamagnetic rod is placed vertically between the poles of an electromagnet. When the current in the electromagnet is switched on, then the diamagnetic rod is pushed up, out of the horizontal magnetic field. Hence, the rod gains gravitational potential energy. The work required to do this comes from
HARD
A conducting loop in the shape of right angled isosceles triangle of height 10 cm is kept such that the 90o vertex is very close to an infinitely long conducting wire (see the figure). The wire is electrically insulated from the loop. The hypotenuse of the triangle is parallel to the wire. The current in the triangular loop is in counterclockwise direction and increased at constant rate of 10 A s-1. Which of the following statement(s) is (are) true?
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EASY
If a coil of metal wire is kept stationary in a uniform magnetic field, then_______.
HARD

In the following circuit the switch Sis closed at t =0. The charge on the capacitor C1 as a function of time will be given by Ceq= C1C2C1+ C2

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EASY
When the current in a coil changes from 5 A to 2 A in 0.1 s, an average voltage of 50V is produced. The self-inductance of the coil is
MEDIUM
A magnetic field of 1 T applied at an angle π3 to the vertical direction is decreased to zero at a steady rate in one second. The magnitude of induced emf in a horizontally placed circular loop of radius 5 cm is given by
EASY
An electron moves on a straight line path XY as shown. The abcd is a coil adjacent to the path of electron. What will be the direction of current, if any, induced in the coil?

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EASY
A 10 m long horizontal wire extends from North East to South West. It is falling with a speed of 5.0 m s-1, at right angles to the horizontal component of the earth's magnetic field of 0.3×10-4 Wb m-2. The value of the induced emf in the wire is:
HARD

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The figure shows a circular area of tthe radius R where a uniform magnetic field B is going into the plane of the paper and increasing in magnitude at a constant rate. In that case, which of the following graphs, drawn schematically, correctly shows the variation of the induced electric field E(r)?

EASY
A solid metal cube of edge length 2 cm is moving in the positive y-direction, at a constant speed of 6 m s-1. There is a uniform magnetic field of 0.1 T in the positive z-direction. The potential difference between the two faces of the cube, perpendicular to the x-axis, is
HARD

A 1 m long thin metal bar of negligible resistance weighing 1 kg rests on two metal supports as shown in the figure. The supports are connected in series to an ideal cell and a resistance. A uniform magnetic field 0.5 T is applied in the region normal to the plane of the paper and into the paper. Maximum emf that the cell can have without breaking the circuit in volt is
(Acceleration due to gravity =10 m s-2 )

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HARD
A circular loop of radius 0.3 cm lies parallel to a much bigger circular loop of radius 20 cm. The centre of the small loop is on the axis of the bigger loop. The distance between their centres is 15 cm. If a current of 2.0 A flows through the smaller loop, then the flux linked with a bigger loop is:
MEDIUM
A straight conductor of length 0.4 m is moving with a speed of 7 ms-1 perpendicular to the magnetic field of intensity of 0.9 Wb m-2. The induced emf across the conductor will be
HARD
A conducting square frame of side a and a long straight wire carrying current I are located in the same plane as shown in the figure. The frame moves to the right with a constant velocity V. The e.m.f induced in the frame (when the centre of the frame is at a distance x from the wire) will be proportional to :
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MEDIUM

A metallic rod of length l is tied to a string of length 2l and made to rotate with angular speed ω on a horizontal table with one end of the string fixed. If there is a vertical magnetic field B in the region, the e.m.f. induced across the ends of the rod is:

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HARD

The figure shows the cross section of a cylindrical region of radius R in which the magnetic field points into the page. The magnitude of the field is 1 T at time t=0 and it decreases to zero in 20 seconds.

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The induced electric field at a distance r from the centre O inside the cylindrical region is given by

HARD

The circular wire in figure below encircles solenoid in which the magnetic flux is increasing at a constant rate out of the plane of the page.

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The clockwise emf around the circular loop is ε0. By definition a voltammeter measures the voltage difference between the two points given
by Vb-Va=-abE·ds. We assume that a and bare infinitesimally close to each other. The values of Vb-Va along the path 1 and Va-Vb along the path 2, respectively are