Magnetism and Matter: Dipole Moment of a Magnet, Gauss՚s Law for Magnetism (For CBSE, ICSE, IAS, NET, NRA 2022)

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  • Many of us also want to know about the interstellar space and its weak magnetic field.
  • We will find out the magnitude of the magnetic moment of a magnet with a certain degree of the uniform magnetic field and what will happen if the magnet is rotated freely in a plane and what will be the potential energy of the magnet.
  • How much torque is required for turning a magnet so that its magnetic moment is at a certain alignment with the field?
  • We will be seeing an example of a magnetic needle used to find out magnetic meridian points and computing the direction and magnitude of the earth՚s magnetic field.
  • There are various examples, exemplary question, MCQ՚S and worksheets mentioned below which will help you understand magnetism and the magnetic field with its uses and application

Dipole Moment of a Magnet

Dipole Moment of a Magnet

The Magnetic Dipole Moment of a Magnetic Dipole is Given by Where, M is Pole Strength and is Dipole Length Directed from s to N.

  • When a magnet is experiencing a dipole moment m, and it is placed in a uniform magnetic field B, then it experiences:
  • The force on it as zero
  • The torque on it as
  • The potential energy can be said to be as - . Where the zero of energy is determined when m is perpendicular to B

Gauss՚s Law for Magnetism

  • This law of magnetism points out the fact that the net magnetic flux through any surface which is closed tends to be Zero.
  • Gauss՚s law for magnetism is one of the four Maxwell՚s equations that underlie classical electrodynamics.
  • It states that the magnetic field B has divergence equal to zero, in other words, that it is a solenoidal vector field.
  • It is equivalent to the statement that magnetic monopoles do not exist.
  • The intensity of a magnetic field, measured in Gauss or Teslas (10,000 Gauss = 1 Tesla) , is also a common measurement of a magnets strength as this is a representation of the density of a magnetic field produced by a magnet, known as flux density.

Components of the Earth՚s Magnetic Field

  • Three components have to be taken care of in order to particularise the earth՚s magnetic field:
  • The horizontal component
  • Magnetic Dip
  • Magnetic Declination

Classification of Magnetic Materials

Classification of Magnetic Materials
  • Magnetic Materials are classified into three types:
  • Diamagnetic- whose χ (magnetic sensitivity of the material) is having negative value and small
  • Paramagnetic- for this the χ is positive and small
  • Ferromagnetic- for this materials, the χ is large

Permanent Magnets

  • When substances are exposed to room temperature, they retain their ferromagnetic properties for a longer time and are called permanent magnets.

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