EASY
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A coil is placed perpendicular to a magnetic field of . When the field is changed to in , an induced emf of is produced in the coil. If the diameter of the coil is , then the number of turns in the coil is:
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Important Questions on Electromagnetic Induction and Alternating Currents
EASY
The magnetic flux through a coil varies with time as . The ratio of emf at to will be
MEDIUM
A circular coil of radius is placed in a uniform magnetic field of with its plane perpendicular to the field initially. It is rotated at constant angular speed about an axis along the diameter of coil and perpendicular to magnetic field so that it undergoes half of rotation in . The maximum value of EMF induced (in ) in the coil will be close to the integer....
EASY
A conducting circular loop is placed in a uniform magnetic field, with its plane perpendicular to the loop. The radius of the loop is made to shrink at a constant rate of . The induced emf when the radius is , is
EASY
A metal disc of radius rotates with a constant angular speed of about its axis. The potential difference between the centre and the rim of the disc under a uniform magnetic field directed perpendicular to the disc, is
MEDIUM
A turn coil of the effective area is kept perpendicular to the magnetic field When the plane of the coil is rotated by around any of its coplanar axis in the emf induced in the coil will be:
MEDIUM
A coil of wire of area containing turns is placed in a magnetic field of induction At time the axis of the coil and the direction of magnetic field are along -direction. The coil is rotated by an angle in about axis. Assuming the constant angular speed, the average e.m.f induced in the coil is approximately
HARD
A light disc made of aluminium (a nonmagnetic material) is kept horizontally and is free to rotate about its axis as shown in the figure. A strong magnet is held vertically at a point above the disc away from its axis. On revolving the magnet about the axis of the disc, the disc will (figure is schematic and not drawn to scale)
MEDIUM
A coil of mean area and having turns is held with its plane perpendicular to a uniform field of . If the coil is turned through in second, then the average induced emf is
HARD
A long solenoid of radius carries a time dependent current . A ring of radius is placed coaxially near its middle. During the time interval the induced current and the induced in the ring change as:
MEDIUM
At time magnetic field of is passing perpendicularly through the area defined by the closed loop shown in the figure. If the magnetic field reduces linearly to in the next then induced in the loop is:
HARD
A wire loop enclosing a semi-circle of radius is located on the boundary of a uniform magnetic field of induction At time , the loop is set into rotation with velocity ? about its axis , coinciding with a line of vector on the boundary as shown in the figure. The emf induced in the loop is
EASY
A coil of cross-sectional area having turns is placed in a uniform magnetic field . When it is rotated with an angular velocity the maximum e.m.f. induced in the coil will be:
MEDIUM
A conducting square loop is placed in a magnetic field with its plane perpendicular to the field. The sides of the loop start shrinking at a constant rate . The induced emf in the loop at an instant when its side is is
EASY
The current in a coil of inductance changes from to in . The magnitude of the average induced emf in the coil is
EASY
A conducting wire bent in the shape of semicircle has length L and moves in its plane with constant velocity v. A uniform magnetic field exists in the direction perpendicular to the plane of the wire. The velocity makes an angle to the diameter joining free ends and the emf induced between the ends of the wire is . The value of constant is
MEDIUM
The magnetic flux linked with a coil varies as . The magnitude of the induced at seconds is
MEDIUM
A conducting circular loop of resistance and cross-sectional area is placed perpendicular to a spatially uniform magnetic field , which varies with time as . Find the net charge flowing through the loop in starting from .
MEDIUM
A planar loop of wire rotates in a uniform magnetic field. Initially, at , the plane of the loop is perpendicular to the magnetic field. If it rotates with a period of about an axis in its plane then the magnitude of induced emf will be maximum and minimum, respectively at:
EASY
In a coil of resistance , 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:
HARD
A conducting square frame of side and a long straight wire carrying current are located in the same plane as shown in the figure. The frame moves to the right with a constant velocity . The e.m.f induced in the frame (when the centre of the frame is at a distance from the wire) will be proportional to :
