HARD
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A thin circular ring of area is held perpendicular to a uniform magnetic field of induction . A small cut is made in ring and a galvanometer is connected across the ends such that total resistance of the circuit is . When the ring is suddenly squeezed to zero area, the charge flowing through the galvanometer is -
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Important Questions on Electromagnetic Induction
HARD
A circular loop of radius lies parallel to a much bigger circular loop of radius . The centre of the small loop is on the axis of the bigger loop. The distance between their centres is . If a current of flows through the smaller loop, then the flux linked with a bigger loop is:
MEDIUM
The magnetic flux linked with a coil, in where, is given by the equation .
Then, the magnitude of induced emf at will be
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?
MEDIUM
A uniform magnetic field is restricted within a region of radius, The magnetic field changes with time at a rate, . Loop one of radius encloses the region, and loop two of radius, is outside the region of magnetic field as shown in the figure below. Then the emf generated is
MEDIUM
In a coil of resistance , the induced current developed by changing magnetic flux through it, is shown in figure as a function of time. 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 :
EASY
A coil of turns, area is placed in an external magnetic field of in such a way that it makes an angle of with field direction. The magnetic flux through the coil will be
MEDIUM
The figure shows a bar magnet and a metallic coil. Consider four situations. (I) Moving the magnet away from the coil. (II) Moving the coil towards the magnet. (III) Rotating the coil about the vertical diameter. (IV) Rotating the coil about its axis.
An emf in the coil will be generated for the following situations.
MEDIUM
A coil of area is placed in a uniform magnetic field of lb. , with its plane perpendicular to the field. The coil rotates at a uniform rate to complete the revolution in . find the average emf . in the coil during intervals when the coil rotates from
i. to position
ii. to position
ii. to position
iv. to position
HARD
A circuit consists of a coil with inductance and an uncharged capacitor of capacitance . The coil is in a constant uniform magnetic field such that the flux through the coil is . At time , the magnetic field is abruptly switched OFF. Let and ignore the resistance of the circuit. Then,
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
Consider a circular coil of wire carrying constant current forming a magnetic dipole. The magnetic flux through an infinite plane that contains the circular coil and excluding the circular coil area is given by The magnetic flux through the area of the circular coil area is given by . Which of the following option is correct?
MEDIUM
A conducting bar of mass and length moves on two frictionless parallel rails in the presence of a constant uniform magnetic field of magnitude directed into the page as shown in the figure.The bar is given an initial velocity towards the right at
Then, the
HARD
A square-shaped conducting wire loop of dimension a moving parallel to the -axis approaches a square region of size where a uniform magnetic field exists pointing into the plane of the paper (see figure). As the loop passes through this region, the plot correctly depicting its speed as a function of is.
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 metal circular-wire-loop of radius is placed perpendicular to a magnetic field which varies with time as where are constants at time . If the resistance of the loop is , then the heat generated in the loop after a long time is
EASY
A long solenoid of diameter has turns per meter. At the centre of the solenoid, a coil of turns and radius is placed with its axis coinciding with the solenoid axis. The current in the solenoid reduces at a constant rate to from in . If the resistance of the coil is the total charge flowing through the coil during this time is
EASY
Assertion (A): Magnetic flux is a vector quantity.
Reason (R): Value of magnetic flux can be positive negative or zero.
MEDIUM
A uniform magnetic field B exists in a direction perpendicular to the plane of a square loop made of a metal wire. The wire has a diameter of and a total length of The magnetic field changes with time at a steady rate The induced current in the loop is close to (Resistivity of the metal wire is )
EASY
When the current in a coil changes from to in , an average voltage of is produced. The self-inductance of the coil is
