page_339

< previous page | page_339 | next page >

Page 339

| Figure 17-6 Dynamometer used as an ammeter (Courtesy, General Electric Co.) |

| voltage is the product of current and resistance. If the resistance is constant, then the value of the current flowing can be taken as a measure of the applied voltage. The magnetic fields set up by this current, therefore, will reflect voltage values. The scale of the ammeter in this case is calibrated to read volts directly, and the instrument is known as a voltmeter. Figure 17-7 shows diagrammatically the connection of a dynamometer type of voltmeter. |

| Figure 17-7 Dynamometer used as a voltmeter (Courtesy, General Electric Co.) |

| Wattmeters |

| The measurement of power by means of an electrodynamometer element is possible because the tendency for rotation (torque) varies with changes in the |

< previous page | page_339 | next page >