Principle: A freely suspended magnetic in a uniform magnetic field aligns in the direction of the field. When it is displaced through a small angle 'θ' in a horizontal plane and released, it experiences a restoring couple. This keeps the magnet in simple harmonic -motionvibrating sample magnetometer(VSM) operates on Faraday's Law of Induction, which tells us that a changing magnetic field will produce an electric field. ... A VSM is used to measure the magnetic behavior of magnetic materialsMagnetometers are measurement instruments used for two general purposes: to measure the magnetization of a magnetic material like a ferromagnet, or to measure the strength and, in some cases, the direction of the magnetic field at a point in space.There are two basic types of magnetometer measurement. Vector magnetometers measure the vector components of a magnetic field. Total field magnetometers or scalar magnetometers measure the magnitude of the vector magnetic field.
Superpostion of Magnetic Fields(B andBH​,Tangent):
When a freely suspended magnet is subjected to an external magnetic field B perpendicular to BH​. Then the needle comes to rest making an angleθwith BH​.thenB=BH​tanθ. This is known as Tangent law.