HARD
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A conducting ring of radius a is kept in x-y plane with its centre at origin. A time varying magnetic field given by B=B0t-k^ is applied in this region. An ideal voltmeter is connected between two points of the ring in two different cases as shown.

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If πB0a2=8 V and voltmeter reading in case I and case II is VI and Vll respectively, then

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Important Questions on Electromagnetic Induction

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
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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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)?

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

EASY
Two small pith balls, each carrying a charge q are attached to the ends of a light rod of length d, which is suspended from the ceiling by a thin torsion free fibre as shown in figure. There is a uniform magnetic field B pointing straight down, in the cylindrical region of radius R around the fibre. The system is initially at rest. If the magnetic field is turned off, which of the following happen to the system -


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EASY
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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HARD
A massless non-conducting rod AB of length 2l is placed in uniform time varying magnetic field confined in a cylindrical regions of radius R>l as shown in the figure. The centre of the rod coincides with the centre of the cylindrical region. The rod can freely rotate in the plane of the figure about an axis coinciding with the axis of the cylinder. Two particles, each of mass m and charge q are attached to the ends A and B of the rod. The time varying magnetic field in this cylindrical region is given by B=B01-t2 where B0 is a constant. The field is switched on at time t=0. Consider: B0=100T, l=4cm, qm=4π100 C kg-1. Calculate the time (in sec) in which the rod will reach position CD shown in the figure for the first time.
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HARD
A conducting ring of radius 1 m is placed in a uniform magnetic field B of 0.01 T oscillating with a frequency of 100 Hz, having its plane at right angle to B. What will be the induced electric field?
HARD

A cylindrical space of radius R, is filled with a uniform magnetic induction B, parallel to the axis of the cylinder. If B changes at a constant rate, the graph showing the variation of induced electric field with distance r, from the axis of cylinder, is

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HARD
Two small pith balls, each carrying a charge q are attached to the ends of a light rod of length d, which is suspended from the ceiling by a thin torsion-free fiber as shown in the figure. There is a uniform magnetic field B pointing straight down, in the cylindrical region of radius R around the fiber. The system is initially at rest. If the magnetic field is turned off, which of the following happens to the system?


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MEDIUM

Represent the union of two sets by Venn diagram for each of the following.

X={x | x is a prime number between 80 and 100}

Y={y | y is an odd number between 90 and 100}

MEDIUM
The resistance in the following circuit is increased at a particular instant. At this instant the value of resistance is 10 Ω. The current in the circuit will be now
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EASY
A uniform but time-varying magnetic field exists in the cylindrical region and directed into the paper. If field decrease with time and a positive charge placed at any point inside the region, then it moves 

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EASY
Two identical circular loops of metal wire are lying on a table without touching each other. Loop A carries a current which increases with time. In response, the loop B,
HARD
A uniform but time varying magnetic field exists in cylindrical region and directed into the paper. If field decreases with time and a positive charge is placed at any point inside the region, then it moves
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HARD

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 in the figure. The magnitude of an induced electric field at the point P at a distance r from the centre of the circular region

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HARD

A conductor is moving with velocity v in a region of uniform magnetic field B. The electric field at P inside conductor is

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MEDIUM
Which of the field pattern given in the figure is valid for electric field as well as for magnetic field?
HARD
A non-conducting ring of mass m and radius R has a charge Q uniformly distributed over its circumference. The ring is placed on a rough horizontal surface such that plane of the ring is parallel to the surface. A vertical magnetic field B=B0t2 tesla is switched on. After 2 s from switching on the magnetic field the ring is just about to rotate about vertical axis though its centre.
HARD

A conducting ring of radius 1 m is placed in a uniform magnetic field B, of 0.01 tesla oscillating with frequency 100 Hz with its plane at right angles to B. What will be the induced electric field?