Which of the following assertions about the magnetic field within a current-carrying solenoid is correct?

A solenoid is a device made out of a wire coil. Because of its geometry, the field within a solenoid is both uniform and highly powerful.

The field right outside the coils is almost non-existent.

Inside a current-carrying solenoid, the magnetic field is relatively homogeneous in direction, but it begins to weaken and change direction near the ends.

The magnetic field strength within a solenoid may be calculated as follows:

$B={\mu }_{\circ }nI$ (inside a solenoid) where is the number of loops per unit of solenoid length, I is the current flowing, and ${\mu }_{\circ }$ is also known as the permeability of open space or the magnetic constant.

Inductors, electromagnets, antennae, valves, and other devices employ solenoids.

Electrical energy is also converted into mechanical work by a solenoid.