Explain the working of a solenoid?

A solenoid is a cylindrical coil of wire that generates a magnetic field when an electric current passes through it. It works on the principle of electromagnetism: when electricity flows through the coiled wire, it produces a magnetic field inside and around the coil, which is strongest and most uniform along the axis inside the solenoid.

How a Solenoid Works

• Current Flow: When electric current passes through the coil, it creates a magnetic field, with the field lines running parallel to the coil's axis inside the solenoid.
• Magnetic Effect: This magnetic field can attract or repel magnetic objects, or it can move a metal plunger or armature placed inside, converting electrical energy into mechanical energy. This movement is harnessed to open or close valves, activate switches, or create movement in electromechanical devices.
• Strength Adjustment: The strength of the magnetic field depends on the number of turns in the coil, the current passing through it, and whether it has an iron core (which increases magnetic strength).
• Reversibility: The direction of the current reverses the direction of the magnetic field, allowing reversible control in applications like relays and valves.
• Return Mechanism: When the current stops, springs or gravity usually return the moving core or plunger to its original position, ready for the next activation.

Example 

• Used in electromagnets, doorbells, starters, relays, and valve control systems.
• Its magnetic field is used wherever precise, controlled actuation is needed using electricity.