Peoples Physics Concepts

http://www.ck12.org Chapter 14. Magnetism

2. Find the magnetic field a distance of 20 cm from a wire that is carrying 3 A of electrical current.


3. In order to measure the current from big power lines the worker simply clamps a device around the wire. This
   provides safety when dealing with such high currents. The worker simply measures the magnetic field and
   deduces the current using the laws of physics. Let’s say a worker uses such a clamp and the device registers a
   magnetic field of 0.02 T. The clamp is 0.05 m from the wire. What is the electrical current in the wire?

Answers to Selected Problems

1. Both pointing away from north


2. 3× 10 −^6 T


3. 5000 A