HARD
Earn 100

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
Question Image  

50% studentsanswered this correctly

Important Questions on Electromagnetic Induction

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 :
Question Image
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:
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
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

Question Image

HARD

Question Image

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)?

MEDIUM
A uniform magnetic field is restricted within a region of radius,  r. The magnetic field changes with time at a rate, dBdt. Loop one of radius R>r encloses the region, r and loop two of radius, R is outside the region of magnetic field as shown in the figure below. Then the emf generated is

Question Image
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:

 Question Image

HARD

A square frame of side 10 cm and a long straight wire carrying current 1 A are in the plane of the paper. Starting from close to the wire, the frame moves towards the right with a constant speed of 10 m s-1 (see figure). The e.m.f induced at the time the left arm of the frame is at x=10 cm from the wire is

Question Image

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
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:
EASY
A coil of cross-sectional area A having n turns is placed in a uniform magnetic field B. When it is rotated with an angular velocity ω, the maximum e.m.f. induced in the coil will be:
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.

Question Image

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

EASY

In a coil of resistance 100 Ω, a current is induced by changing the magnetic flux through it as shown in the figure. The magnitude of change in flux through the coil is:
Question Image

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
EASY
A long solenoid of diameter 0.1 m has 2×104 turns per meter. At the centre of the solenoid, a coil of 100 turns and radius 0.01 m is placed with its axis coinciding with the solenoid axis. The current in the solenoid reduces at a constant rate to 0 A from 4 A in 0.05 s. If the resistance of the coil is 10π2 Ω, the total charge flowing through the coil during this time is
HARD
A conducting metal circular-wire-loop of radius r is placed perpendicular to a magnetic field which varies with time as B=B0e-tτ, where B0 and τ are constants at time t=0. If the resistance of the loop is R, then the heat generated in the loop after a long time t is
HARD
Consider a thin metallic sheet perpendicular to the plane of the paper moving with speed v in a uniform magnetic field B going into the plane of the paper (see figure). If charge densities σ1 and σ2 are induced on the left and right surfaces respectively of the sheet, then (ignore fringe effects)

Question Image
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 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?
Question Image
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.

Question Image

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