Chapter 19 - Magnetism - Learning Path Questions and Exercises - Conceptual Questions - Page 690: 27

The core helps in concentrating the magnetic lines of forces through the solenoid so that the magnetic field is almost uniform at the end face of the core. In the absence of a core, the magnetic lines of forces start to diverge by curving sharply immediately outside the coils.

The core helps in concentrating the magnetic lines of forces through the solenoid so that the magnetic field is almost uniform at the end face of the core. In the absence of a core, the magnetic lines of forces start to diverge by curving sharply immediately outside the coils.