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A copper connector of mass m slides down two smooth copper bars, set at an angle α to the horizontal, due to gravity. At the top, the bars are interconnected through a capacitor, of capacitance C. The separation between the bars is equal to l. The system is located in a uniform magnetic field of induction B, perpendicular to the plane in which the connector slides. The resistances of the bars, the connector and the sliding contacts as well as the self-inductance of the loop, are assumed to be negligible. Find the acceleration of the connector.

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Important Questions on ELECTRODYNAMICS

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JEE Main
IMPORTANT

A wire shaped as a semi-circle of radius a, rotates about an axis OO' with an angular velocity ω, in a uniform magnetic field of induction B. The rotation axis is perpendicular to the field direction. The total resistance of the circuit is equal to R. Neglecting the magnetic field of the induced current, find the mean amount of thermal power being generated in the loop during a rotation period.

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JEE Main
IMPORTANT
A small coil is introduced between the poles of an electromagnet, so that its axis coincides with the magnetic field direction. The cross-sectional area of the coil is equal to S=3.0 mm2, the number of turns is N=60. When the coil turns through 180° about its diameter, a ballistic galvanometer, connected to the coil, indicates a charge q=4.5 μC flowing through it. Find the magnetic induction magnitude between the poles, provided the total resistance of the electric circuit equals R=40 Ω.
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JEE Main
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A square wire frame with side a and a straight conductor carrying a constant current I are located in the same plane . The inductance and the resistance of the frame are equal to L and R respectively. The frame was turned through 180° about the axis OO' separated from the current-carrying conductor by a distance b. Find the electric charge having flown through the frame.

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JEE Main
IMPORTANT

A long straight wire carries a current, I0. At distances a and b from it there are two other wires, parallel to the former one, which are interconnected by a resistance, R. A connector slides without friction, along the wires, with a constant velocity, v. Assuming the resistances of the wires, the connector, the sliding contacts and the self-inductance of the frame to be negligible, find,
a the magnitude and the direction of the current induced in the connector;
b the force required to maintain the connector's velocity constant.

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JEE Main
IMPORTANT

A conducting rod AB, of mass m, slides without friction over two long conducting rails, separated by a distance I . At the left end, the rails are interconnected by a resistance R. The system is located in a uniform magnetic field, perpendicular to the plane of the loop. At the moment t=0, the rod AB starts moving to the right with an initial velocity v0. Neglecting the resistances of the rails and the rod AB, as well as the self-inductance, find,
a the distance covered by the rod until it comes to a standstill,
b the amount of heat generated in the resistance R during this process.

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JEE Main
IMPORTANT

A connector AB can slide, without friction, along a Π-shaped conductor, located in a horizontal plane. The connector has a length I, mass m and resistance R. The whole system is located in a uniform magnetic field of induction B, directed vertically. At the moment t=0, a constant horizontal force F starts acting on the connector, shifting it translation-wise, to the right. Find how the velocity of the connector varies with time t. The inductance of the loop and the resistance of the Π-shaped conductor are assumed to be negligible.

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JEE Main
IMPORTANT

Figure illustrates plane figures made of thin conductors which are located in a uniform magnetic field, directed away from a reader, beyond the plane of the drawing. The magnetic induction starts diminishing. Find how the currents induced in these loops are directed.

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JEE Main
IMPORTANT

A plane loop shown in the figure is shaped as two squares with sides, a=20 cm and b=10 cm, and is introduced into a uniform magnetic field at right angles to the loop's plane. The magnetic induction varies with time as B=B0sinωt, where B0=10 mT and ω=100 s-1. Find the amplitude of the current induced in the loop, if its resistance per unit length is equal to ρ=500  m-1. The inductance of the loop is to be neglected. 

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