Explain the properties of high resistivity materials.
High resistivity materials: The conducting materials containing resistivity from 10-6 to 10-3 ohm-m come under such category and is used for making resistance components for heating devices, rheostats and precision instruments.
Examples are: Constantian, Nichrome and Mangnesium.
Properties:
Low temperature coefficient: In voltage drop and power loss for minimum variations with the change in temperature, such materials must have low temperature coefficient.
High mechanical strength: These materials should withstand the mechanical stresses developed throughout its use for specific applications.
Ductility: The material to be utilized, as conductors should be ductile so that this can be drawn and moulded in different shapes and sizes.
High melting point: These materials that are used as heating elements must have high melting point.
Oxidation resistance: The material must have an oxidation resistanceso that this must get oxidized when used in various environmental conditions.