This chapter introduces the students to the concept of magnetic field, Oersted’s experiment, Biot - Savart law and its various application, Ampere's law and its applications, straight and toroidal solenoids and force on a moving charge in uniform fields. The principle of the cyclotron, the force on a current-carrying conductor, torque experienced by a current loop and the principle and working of a moving coil galvanometer are some other topics covered in this chapter.