Magnetostriction

The effect was first identified in 1842 by James Joule when observing a sample of iron.

Q. What is Magnetostriction?

A. Magnetostriction (cf. electrostriction) is a property of ferromagnetic materials that causes them to change their shape or dimensions during the process of magnetization.

Q.What are Ferromagnetic substances?

A. Materials that can be magnetized by an external magnetic field and remain magnetized after the external field is removed are called either ferromagnetic or ferrimagnetic .e.g-Iron, Nickel, Cobalt etc.

Q.What is the full form of LASER?

A.Light Amplification by Stimulated Emission of  Radiation.

Q.What are magnetostriction substances?

A.Those substances which are capable of converting magnetic energy into kinetic energy are called magnetostriction substances.

Q.Why does magnetostriction occur?

A.Ferromagnetic substances contain domains i.e. regions of uniform magnetic field. In presence of external magnetic field the boundary of domains disappear and the domain can shift and rotate as such objects can change their shape and size..

Q.Define interference.

A. Interference is a phenomenon in which two waves superpose to form a resultant wave of greater or lower amplitude.

Q.What is the use of Michelson interferometer?

A.Michelson Interferometer is a device to generate interference. The change in the length of material due to its magnetostriction property is of the order of 10^-6 as such we can not see the change by naked eyes thus we have  to rely on the formation of interference patterns to detect the change in the material.

Michelson Interferometer is the most common and widely used configuration for optical interferometry and was invented by Albert Abraham Michelson.It produces interference fringes by splitting a beam of monocromatic light.

Q.What kind of interference takes place?

A.Interference takes place by amplitude as the light from laser is partially reflected and partially refracted and the interference pattern is formed by the combination of these two rays.

Q.Why do we get circular ring?

A.Due to constant  phase difference.The mirrors M1 and M2 are perpendicular thus a virtual image is formed which acts as an extended source thus we get circular rings.

Q.Why do we use solenoid ?

A. Solenoid is a cylindrical coil of wire acting as a magnet when carrying electric current. Thus it is used to generate magnetic field which is responsible for shortening or lengthening of the material.

Q.Why do we use red laser?

A.Due to high wavelength and the fringes formed are darker.

Q.How does change in length create interference?

A.The rod is connected to beam splitter thus any change no matter how small will effect the position of the beam splitter thus resulting in creation of interference patterns.

Q.What is Positive and negative magnetostriction?

A.When the material elongates under the influence of external magnetic field it is called positive magnetostriction and when it shrinks it is called negative magnetostriction.

Some last points:

1.The light should originate from an extended source.A point source will not produce the desired fringes in this case.

2.Do study about Michelson Interferometer and about interference.

3.Read about different types of magnetic substances and their properties.

Megnetostrictions

 

 

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