An elementary book on electricity and magnetism and their applications . sists of an electromagnet, an armature,and a commutator with its brushes. To understand how theseact in the motor, however, we must get a clear idea of the be-havior of a wire carrying an electric current in a magneticfield. We shall see that the motion of a motor is due to thereaction between (1) the current flowing in a set of conductorsmounted on an armature, and (2) a magnetic field in which theconductors and their armature rotate. The motor exerts itsmechanical effort or torque as a pull on a belt, or thrust on agear
An elementary book on electricity and magnetism and their applications . sists of an electromagnet, an armature,and a commutator with its brushes. To understand how theseact in the motor, however, we must get a clear idea of the be-havior of a wire carrying an electric current in a magneticfield. We shall see that the motion of a motor is due to thereaction between (1) the current flowing in a set of conductorsmounted on an armature, and (2) a magnetic field in which theconductors and their armature rotate. The motor exerts itsmechanical effort or torque as a pull on a belt, or thrust on agear, or as a twisting force on a shaft. The input of an electricmotor is electric power and the output is mechanical power. 231 232 ELECTRICITY AND MAGNETISM 158. Side push of a magnetic field on a wire carrying acurrent. Suppose we streteh a flexible wire loosely between twobinding posts A and B, so that a section of the wire lies betweenthe poles of an electromagnet, as shown in figure 161. Let the ex-citing current be so connected with the electromagnet that the poles. Fig. 161. — Side push on wire carrying a current. are N and S as shown. Then, if a strong current from a storagebattery is sent through the wire from A to B by closing the switch, itwill be seen that the wire between the magnets poles is instantlythrown upward. If the current is sent from B to A, the motion of thewire is reversed, and it is thrown downward. To understand this side push exerted on acurrent-carrying wire in a magnetic field, letus recall that every current generates a mag-netic field of its own, the lines of which are Fig. 162. — Mag- ... nc. , netic field about concentric circles. Figure 162 shows a wire a currentinto, that is, at rightangles to, the paper and away fromus. The lines of force are goingaround the wire in clockwise direc-
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectmagnetism, bookyear19
