D.A.V. PUBLIC SCHOOL ASSANDH ,KARNAL

DEPARTMENT OF PHYSICS

CERTIFICATEThis is to certify that KAWAM SHARMA XII-Medical has successfully completed the project report on HYSTERISIS CURVE under the guidance of MR. DINESH SHARMA during the year 2016-2017 in partial fulfillment of physics practical examination conducted by AISSCE ,New- Delhi

(Principal Sir)

(Subject Teacher)

ACKNOWLEDGEMENT I have taken efforts in this project. However, it

would not have been possible without the kind support and help of many individuals. I would like to extend my sincere thanks to all of them.

I am highly thankful to Mr. Dinesh Sharma for their guidance and constant supervision as well as for providing necessary information regarding the project & also for their support in completing the project.

I would like to express my gratitude towards my parents for their kind co-operation and encouragement which help me in completion of this project.

I would like to express my special gratitude and thanks to Principal Sir for giving me such attention and time.

My thanks and appreciations also go to my colleague in developing the project.

KAWAM SHARMA

INDEXI. CERTIFICATE OF EXCELLECNEII. ACKNOWLEDGEMENTIII. AIM OF PROJECTIV. INTRODUCTIONV. HYSTERISIS CURVE/LOOPVI. COERCIVITY AND REMANENCEVII. VARIATIONS IN HYSTERISIS CURVEVIII.ENERGY DISSIPATION DUE TO HYSTERESISIX. HYSTERESIS CURVE FOR STEEL AND SOFT IRON COREX. APPLICATIONSXI. BIBILIOGRAPHY

AIM OF THE PROJECT

To study the HYSTERISIS CURVE and its applications.

INTRODUCTION The lagging of intensity of magnetization (I) or magnetic

induction (B) behind magnetizing field (H), when a specimen of a magnetic substance is taken through a complete cycle of magnetization is called hysteresis.

A hysteresis loop shows the relationship between the induced magnetic flux density (B) and the magnetizing force (H). It is often referred to as the B-H loop.

Hysteresis loop • To start with the iron core placed in a solenoid having no

current. Now current is flowing in the solenoid increases gradually. This magnetic field is called magnetizing field (H). As the value of H is increases magnetic flux density (B) also increases. The variation of B with H is shown by first curve. Further increase in current in solenoid increases the value of H but not of B. Thus point of saturation is obtained.

• Now ,reduce the value of current in the solenoid till the value of H becomes zero.]The iron core placed inside the solenoid begins to demagnetize. When H=0, B not 0. It shows magnetic material retains magnetism however if H is 0. This property is c/a retentivity

• Now reverse the direction of flow of electrons in the solenoid, so that the H acts in opposite direction. The magnetic field B of the magnetic material decreases. The magnetic field B becomes 0. This magnetizing field H needed to completely demagnetize the material is called coercivity.

• The value of current in he solenoid is further increased in the same direction, so the value of increases further. The value of B also increases in the reverse direction i.e., along y axis. In other words, magnetic material begins to magnetize in opposite direction till it is completely magnetized. Now repeat above steps.

Coercivity and Remanence When a ferromagnetic material is magnetized in one direction, it

will not relax back to zero magnetization when the imposed magnetizing field is removed. The amount of magnetization it retains at zero driving field is called its remanence.

It must be driven back to zero by a field in the opposite direction; the amount of reverse driving field required to demagnetize it is called its coercivity.

Variations in Hysteresis CurvesThere is considerable variation in the hysteresis of different magnetic materials.

ENERGY DISSIPATION DUE TO HYSTERESIS

During the cycle of magnetization and demagnetization of magnetic substance, energy is spent. This energy appears as the heat in the

substance. Such energy loss is known as the hysteresis loss. The loss of energy per unit volume of the substance is equal to the area of B-

H curve.

The study of hysteresis curve of a given substance helps us to know different properties of substance. For instance form hysteresis curve of a given material its retentivity, coercivity, susceptibility, permeability and energy loss per cycle of magnetization can be calculated.

HYSTERESIS CURVE FOR STEEL AND SOFT IRON CORE

i. The retentivity of soft iron is more than the retentivity of steel

ii. Coercivity of soft iron is less than the coercivity of steel

iii. Soft iron can be easily demagnetize as compared to steel

iv. Area of loop for iron is less then the area of steel, therefore hysteresis loss in case of steel is greater than soft iron core

APPLCATIONS

• There are a great variety of applications of the hysteresis in ferromagnets. Many of these make use of their ability to retain a memory, for example magnetic tape, hard disks, and credit cards. In these applications, hard magnets (high coercivity) like iron are desirable so the memory is not easily erased.

• Soft magnets (low coercivity) are used as cores in electromagnets. The nonlinear response of the magnetic moment to a magnetic field boosts the response of the coil wrapped around it. The low coercivity reduces that energy loss associated with hysteresis.

• In neuroscience some neurons do not return to their basal conditions from a stimulated condition immediately after removal of the stimulus is an example of hysteresis.

BIBILIOGRAHY

1. WWW.GOOGLE.COM2. WWW.SCRBID.COM3. NCERT 124. DINESH MILLENNIUM PHYSICS -XII

Submitted To :- Dinesh Sir Submitted By :- KAWAM SHARMA XII-MEDICAL

PHYSICS

PROJECT REPORT ON HYSTERISIS LOOP

2016-2017