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Fig. 1: Eddy current dynamometer.

Working Principle of Eddy Current Dynamometer

Eddy current dynamometer is electrical absorption dynamometer working on principle that, when isolated conductor moves through magnetic flux, it induces eddy current, which get dissipated in the form of heat.

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Figure 1: Liquid in Glass Thermometer.

Construction & Working of Liquid in Glass Thermometer

Liquid in Glass Thermometer consists of glass envelope filled in with liquid and calibrated indicating scale marked on it. The envelope comprises a thick walled glass tube with a capillary bore and a spherical or cylindrical bulb filled with liquid.

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Fig. 1: Bimetallic Thermometer (Bimetallic strip in spiral form)

Working Principle of Bimetallic Thermometer

Two different materials having different coefficient of thermal expansion rigidly joined together, one on other to form a bimetallic strip. 

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Figure 1: McLeod Gauge.

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Figure 1: Hot-Cathode Ionization Gauge.

Working Principle of Ionization Gauge

The basic principle of an ionization gauge is the electrons emitted from a cathode strikes a gas molecule and knocks out an electron from it. Thus the gas molecule remains as a positively charged ion and carries a current called ion current. This current become a measure of the applied pressure when calibrated.

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Working Principle of Thermocouple Vacuum Gauge

The operating principle of thermocouple Vacuum Gauge is that the conducting ability of gas in vacuum or low pressure depends on the pressure i.e., it is a function of pressure. The measurement of vacuum using  thermocouple gauge is shown in figure 1.

Figure 1: Thermocouple Vacuum Gauge.

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