Hint: A solenoid is a type of electro-magnet which consists of a cylinder wrapped up with coil. It is used to create a uniform magnetic field. Since it is a type of electromagnet hence, we can use it to produce magnetic fields of different strengths. In a solenoid the wire is connected to a source by which a current flow through a wire and produces magnetic field
The above figure shows the diagram of the cylindrical part of the solenoid. As we can see that due to the current carrying wire a magnetic field is produced in it and hence it acts like an electromagnet. As in the above figure we can see that the magnetic field is curved outside the cylindrical part of the solenoid but is in the form of a straight line inside the cylindrical part. The straight line fields show that they are uniform. This pattern of the field line shows that the magnetic fields are uniform and in a form of straight line inside the solenoid and are non-uniform and curved outside the solenoid. This device is really important and the fact that it produces a uniform magnetic field inside the cylindrical part makes it more important, from locking of doors to a gearbox we use solenoid in our everyday life.
Note: A solenoid is very useful in our everyday life. We use solenoid in inductors, electromagnets, antennas and many more devices that play a very important role in our everyday life. Solenoid is based on the simple principle of electromagnetism that a magnetic field is produced by a current carrying wire or conductor.