In this worksheet, we will practice using the Biot–Savart law and Ampere's law to calculate the magnetic field produced by a toroid.

**Q1: **

A toroid with a square cross section has an inner radius of 25.0 cm. It is wound with 500 turns of wire, and it carries a current of 2.0 A. What is the strength of the magnetic field at the centre of the square cross section?

- A 0.67 mT
- B 0.90 mT
- C 0.50 mT
- D 0.80 mT
- E 0.33 mT

**Q2: **

A toroid has an inner radius of 20.0 cm and an outer radius of 22.0 cm. The toroid is tightly wound with one layer of 0.250-mm-diameter wire.

How many turns are there on the toroid?

- A
- B
- C
- D
- E

If the current through the toroid windings is 2.0 A, what is the strength of the magnetic field at the centre of the toroid?

- A 0.10 T
- B 0.25 T
- C 0.20 T
- D 0.16 T
- E 0.32 T

**Q3: **

There is a current of 1.5 A through the windings of a large, thin toroid with 200 turns per meter. If the toroid is filled with iron for which the magnetic susceptibility is , what is the magnetic field within it?

- A T
- B T
- C
- D T
- E T