# Worksheet: Self-Inductance of a Long Solenoid

In this worksheet, we will practice calculating the self-inductance of a cylindrical solenoid and the emf induced by it when the current through it varies with time.

**Q3: **

A cylindrical solenoid is wrapped around an iron core. The self-inductance of the solenoid is given by where is the solenoid’s length, its cross-sectional area, and is the number of its turns. The solenoid’s core has a magnetic susceptibility of and the current in the solenoid is 2.0 A.

What is the strength of the magnetic field in the core?

What is the effective surface current formed by the atomic current loops in the core?

What is the self-inductance of the solenoid?