Question

What is a solenoid and what is its function?

Answer 1

The solenoid is a long cylindrical coil of wire consisting of a large no. of turns bound together very tightly.
The length of the coil should be longer than its diameter.
It is a coil of a number of turns of insulated copper wire closely wrapped in shape of a cylinder.
Theses appear to be similar to that of a bar magnet.
One end of the Solenoid behaves like North Pole and the other end behaves like the South Pole. Magnetic field lines inside the solenoid are in the form of parallel straight lines.
This means that the field is same at all the points inside the solenoid.
When soft iron rod is placed inside the solenoid, it behaves like an electro magnet. The use of soft iron as core in the solenoid produces the strongest magnetism.

USES
Solenoids are used to make electromagnets
They are made use of in speakers and microphones
They are used in hotel door locks
They find application in MRI machines, making of hard drives , powerplants, air conditioning systems
They are made use of for making transformers