Table of contents

SOLENOID:

Solenoids are basically electromagnets, they are made of a big coil of wire wound in the form of helical coils, When the current flows through the coil, magnetic field is generated in it, The magnetic field is strong along the axial line of the solenoid. The core in the center is made from a ferromagnetic material.

EXPRESSION FOR MAGNETIC FIELD INSIDE A SOLENOID :

The amperean loop in the following image is the rectangular closed path abcd which is under consideration. Here ab = cd = l is the length of the rectangle. At various turns of the coil current comes out of the plane of the screen/paper which are marked as dot. At various turns of the coil current enters the plane of the screen/paper, which are marked as cross.

THE MAGNETIC FIELD INSIDE A CLOSELY WOUND LONG SOLENOID IS UNIFORM EVERYWHERE BUT ZERO OUTSIDE THE COIL.

AMPERE CIRCUITAL LAW :

APPLYING AMPERE CIRCUITAL LAW:

CONCLUSION

The Biot-Savart law and the superposition principle are used to obtain the magnetic field expression for a long solenoid, which is only valid inside the solenoid.The fundamental outcome of electromagnetism is this phrase.In terms of the number of turns per unit length, the amount of current flowing through the solenoid, and the distance from the solenoid’s centre, this formula represents the magnetic field inside the solenoid. Because the magnetic field within the solenoid is uniform and directed parallel to the solenoid’s axis, applications like magnetic resonance imaging and electromechanical devices can be made with it.