Solenoid: Class 12 Physics Notes, Definition, Types & Working Principle

Solenoid working principle is based on electromagnetism. The magnetic field is created around the solenoid when current passes through it. Inside the solenoid, a moving ferromagnetic material (like iron), which is called a plunger, is placed. The magnetic field pulls the plunger towards the centre of the coil, which converts the electrical energy into linear mechanical motion. Below is a detailed explanation of a solenoid.

A solenoid contains a large number of circular loops wrapped around a non-conducting cylinder.
(it may be a hollow cylinder or it may be a solid cylinder)

         

(ii) The winding of the wire is uniform direction of the magnetic field is same at all points of the axis.

(iii) $\vec{B}$ on axis (turns should be very close to each others).

B = $\frac{{\mu }_{0}ni}{2}$  (cos Θ₁ – cos Θ₂)                             

Note :

Use right hand rule for direction (same as the direction due to loop).

Take an element of width dx at a distance x from point P. [point P is the point on the axis at which we are going to calculate the magnetic field. Total number of turns in the element dn = ndx where n is: number of turns per unit length.