MEDIUM
Earn 100

The geometric length of a bar magnet is 24 cm. The length of the magnet is

50% studentsanswered this correctly

Important Questions on Matter and Magnetism

HARD
Physics>Electricity and Magnetism>Matter and Magnetism>Bar magnet
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:
MEDIUM
Physics>Electricity and Magnetism>Matter and Magnetism>Bar magnet
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>Matter and Magnetism>Bar magnet
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:
EASY
Physics>Electricity and Magnetism>Matter and Magnetism>Bar magnet
Inside a bar magnet, the magnetic lines of force
EASY
Physics>Electricity and Magnetism>Matter and Magnetism>Bar magnet
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
MEDIUM
Physics>Electricity and Magnetism>Matter and Magnetism>Bar magnet
∮B→·ds→=0 equation is not according to the following
EASY
Physics>Electricity and Magnetism>Matter and Magnetism>Bar magnet
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:
EASY
Physics>Electricity and Magnetism>Matter and Magnetism>Bar magnet

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 :

HARD
Physics>Electricity and Magnetism>Matter and Magnetism>Bar magnet
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>Matter and Magnetism>Bar magnet
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):

Question Image
MEDIUM
Physics>Electricity and Magnetism>Matter and Magnetism>Bar magnet
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
MEDIUM
Physics>Electricity and Magnetism>Matter and Magnetism>Bar magnet
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.
Question Image
Given that there is a neutral point it is located in,
EASY
Physics>Electricity and Magnetism>Matter and Magnetism>Bar magnet
A magnet of pole strength m and length l is broken into two pieces. The pole strength of each piece is
MEDIUM
Physics>Electricity and Magnetism>Matter and Magnetism>Bar magnet
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
HARD
Physics>Electricity and Magnetism>Matter and Magnetism>Bar magnet
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
EASY
Physics>Electricity and Magnetism>Matter and Magnetism>Bar magnet
In a bar magnet, the ratio of magnetic length to geometrical length is nearly
EASY
Physics>Electricity and Magnetism>Matter and Magnetism>Bar magnet
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 
EASY
Physics>Electricity and Magnetism>Matter and Magnetism>Bar magnet
In a permanent magnet at room temperature
EASY
Physics>Electricity and Magnetism>Matter and Magnetism>Bar magnet
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:
HARD
Physics>Electricity and Magnetism>Matter and Magnetism>Bar magnet
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)