# physics

posted by
**dd** on
.

A coil consists of N=105 turns of wire wrapped uniformly around a plastic torus. The inside radius of the torus is r0=0.12 m and the outer radius is r1=0.14 m. Thus, each winding has a diameter d=0.02 m. What is the self-inductance (in H) of this coil? Work in the approximation d≪r0.