Ques. What is the object of the field magnet?
Ans. To provide a magnetic field, through which the conducting loops arranged on a central hub and forming the armature are carried, or the flux carried through them, so that they are successively filled and emptied of magnetic lines.
Ques. What is a commutator?
Ans. A device for causing the alternating currents generated in the armature to flow in the same direction in the external circuit.
Ques. Upon what does the voltage depend?
Ans. Upon the rate at which each conducting loop is filled and emptied of lines of force and the number of such loops with their grouping or connection.
Ques. How is the operation of a dynamo best explained?
Ans. By considering first the action of the simplest form of current generator, or elementary alternator.
Ques. Describe an elementary alternator.
Ans. It consists, as shown in fig. 165, of a single rectangular loop of wire A B C D, one end being attached to a ring F and the other to the shaft G, and arranged so as to revolve around the axis X X′, which is located midway between the two poles of the magnet. Two metallic strips or brushes M and S connected with the external circuit, bear on the ring F and shaft G, respectively, in order to “collect” the current generated in the armature when the machine is in operation. The long, straight, horizontal arrows joining the two poles of the magnet, represent the lines of force which make up the magnetic field between the poles. The field is here assumed to be uniform, as indicated by the equal spacing of the arrows.