Question

explain what is a solenoid briefly?

Answer 1

Acoil of wire wound inthe form of helix is  solenoid

Answer 2

In physics, we we solenoid to create a uniform magnetic field in a cylindrical region. The radius is small  and length of cylindrical shape is long.

It is used a strong electromagnet. Usually a long thin insulated conducting wire is wound around a hollow cylindrical conductor or non-conductor.  The wire strands are wound in a helix with the windings very close to each other.

To increase magnetic effect, a soft iron  cylinder may be present inside the windings of a solenoid. Inside the solenoid, the magnetic field is  nearly uniform.