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Assertion: The net magnetic flux coming out of a closed surface is always zero.

Reason: Unlike poles of equal strength exist together.

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Important Questions on Magnetism and Matter

MEDIUM
Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law
An electron is moving along +x direction with a velocity of 6×106ms-1. It enters a region of uniform electric field of 300 V/cm pointing along +y direction. The magnitude and direction of the magnetic field set up in this region such that the electron keeps moving along the x direction will be:
HARD
Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law
An electron gun is placed inside a long solenoid of radius R on its axis. The solenoid has n turns/length and carries a current I. The electron gun shoots an electron along the radius of the solenoid with speed v. If the electron does not hit the surface of the solenoid, maximum possible value of v is (all symbols have their standard meaning):

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EASY
Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law
A small bar magnet is placed with its axis at 30o with an external magnetic field of 0.06 T experiences a torque of 0.018 Nm. The minimum work required to rotate it from its stable to unstable equilibrium position is:
MEDIUM
Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law
∮B→·ds→=0 equation is not according to the following
HARD
Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law
The magnetic flux near the axis and inside the air-core solenoid of length 60 cm carrying current I is 1.57×106 Wb. Its magnetic moment will be (cross-sectional area of a solenoid is very small as compared to its length, μ0=4π×10-7 SI units)
MEDIUM
Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law
A thin rod of length L is magnetized and has magnetic moment M. The rod is then bent in a semicircular arc. The magnetic moment in the new shape is
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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law
In a permanent magnet at room temperature
HARD
Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law
A bar magnet of length 14 cm is placed in the magnetic meridian with its north pole pointing towards the geographic north pole. A neutral point is obtained at a distance of 18 cm from the center of the magnet. If BH=0.4 G, the magnetic moment of the magnet is 1 G=10-4 T
MEDIUM
Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law
Two identical bar magnets are held perpendicular to each other with a certain separation, as shown below. The area around the magnets is divided into four zones.
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Given that there is a neutral point it is located in,
EASY
Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law
A circular coil having N turns and radius r carries a current I. It is held in the XZ plane in a magnetic field Bi^ . The torque on the coil due to the magnetic field is:
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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law
Inside a bar magnet, the magnetic lines of force
MEDIUM
Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law
An insulating thin rod of length l has a linear charge density ρx=ρ0xl on it. The rod is rotated about an axis passing through the origin x=0 and perpendicular to the rod. If the rod makes n rotations per second, then the time averaged magnetic moment of the rod is:
MEDIUM
Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law
Two short bar magnets of moments 512 A m2 and 1000 A m2 are placed coaxially 18 cm apart. The magnetic field is zero at a point Q between them. The field at Q, when one of the magnets is reversed pole to pole is
EASY
Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law
The net magnetic flux through any closed surface is:
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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law
A magnet of pole strength m and length l is broken into two pieces. The pole strength of each piece is
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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law
A large magnet is broken into two pieces so that their lengths are in the ratio 1:2. The ratio of their magnetic moments is 
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Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law

Which of the following statements are correct?
(A) Electric monopoles do not exist whereas magnetic monopoles exist.
(B) Magnetic field lines due to a solenoid at its ends and outside cannot be completely straight and confined.
(C) Magnetic field lines are completely confined within a toroid.
(D) Magnetic field lines inside a bar magnet are not parallel.
(E) χ=-1 is the condition for a perfect diamagnetic material, where χ is its magnetic susceptibility.

Choose the correct answer from the options given below :

EASY
Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law
The magnetic dipole moment of a short magnetic dipole at a distant point along the equator of magnet has a magnitude of X in SI units. If the distance between point and the magnet is halved then the magnitude of dipole moment will be
HARD
Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law
Two short bar magnets of length 1cm each have magnetic moments 1.20 A m2 and 1.00 A m2 respectively. They are placed on a horizontal table parallel to each other with their N poles pointing towards the south. They have a common magnetic equator and are separated by a distance of 20.0 cm. The value of the resultant horizontal magnetic induction at the mid-point O of the line joining their centres is close to
( Horizontal component of earth's magnetic induction is 3.6×10-5  Wb m-2 )
HARD
Physics>Electricity and Magnetism>Magnetism and Matter>Magnetism and Gauss's Law
A hoop and a solid cylinder of same mass and radius are made of a permanent magnetic material with their respective axes. But the magnetic moment of hoop is twice of solid cylinder. They are placed in a uniform magnetic field in such a manner that their magnetic moments make a small angle with the field. If the oscillation periods of hoop and cylinder are Th and Tc respectively, then: