Small Motors, Transformers, Electromagnets; A Practical Presentation of Design and Construction Data for Small Motors, Small Low- And High-Tension Tra

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1920 Excerpt: ... cause AB to actually move to the left, thus reducing the number of lines of force, a pressure will simultaneously be induced in the circuit, according to the right-hand rule, in a clockwise direction, or directly opposite to that of the applied pressure of battery E. This clockwise induced pressure due to the motion of AB sends a current around the circuit in a clockwise direction. The Fig. 7. Graphic Representation of Effect of Motion on Induced Currents resultant current in the circuit must therefore be the difference between the current produced by the battery and that resulting from the induced pressure. Whenever the conductor AB stops moving, there is no induced pressure and hence no induced current, and the current in the circuit is simply one whose value may be expressed by Ohm's law '-f in1 which / denotes the current, in amperes, in the circuit, E denotes the pressure, in volts, applied to the circuit, and R denotes the resistance, in ohms, of the complete circuit. Whenever the conductor AB is moving to the left, the current in the circuit is less than when the conductor is stationary. When the conductor is in motion, the current may be expressed by in which I' denotes the current in the circuit, E the applied pressure, and R the total resistance as before, but e denotes the induced pressure which, according to the right-hand rule, is directly opposite in direction to the applied battery pressure. Because of its opposite direction this pressure is called the counterelectromotive force; and, being produced by induction or relative motion between an inductor and a magnetic field, it is called the electromotive force of induction. If the direction of the current around the circuit ABDEF is reversed, the movable portion AB will move to the right, acco...