College Physics 10th Edition by Raymond Serway,Chris Vuille

Exercise 20

A straight wire carrying a 3.0-A current is placed in a uniform magnetic field of magnitude 0.28 T directed perpendicular to the wire. (a) Find the magnitude of the magnetic force on a section of the wire having a length of 14 cm. (b) Explain why you can't determine the direction of the magnetic force from the information given in the problem.