Temperature Effect on Conductors, Semiconductors & Insulators -The resistance of the conductor increase with an increase of temperature. Whereas, the resistance of semiconductors and insulators decreases with an increase in temperature.
The resistance of the substance either decreases or increases with a rise in temperature. In metallic substances- like aluminum, copper, silver, etc.- the resistance increases with an increase in the temperature.
The resistance of the conductor increase with the increase in temperature because of the increased collision between electrons & the atom. The collision between the electrons and atom causes hindrance of the movement of the electrons. Thus, the resistance increases. The temperature coefficient of resistance of the metallic substance is positive.
In semiconductors like germanium and silicon, the numbers of free electrons in the valence band increase because of the breaking of the covalent bond at increased temperature. Thus, more electrons from the valence band reach the conduction band. As a result, the resistance of the semiconductor material decrease with an increase in temperature.
Similarly, the resistance of the insulating material decrease with an increase in temperature. The below-given graph shows the relationship between the change in the resistance and temperature rise for three categories of material widely used for electrical application.
Effect of Temperature on Materials
We can divide the substances into the following categories based on the resistance. we will discuss in detail the Effect of Temperature on the Conductor, Semiconductor & Insulator in the subsequent sections.
Resistance of Conductor
The metallic substances offer very little resistance to the current flowing through them and these substances are called conductors. Silver and copper have much less resistance than the resistance of aluminum.
Aluminum is used widely in electrical applications because of its lower cost and lower specific weight. The metallic substances have a positive temperature coefficient of resistance. The resistance of metals increases linearly with an increase in temperature as shown in the below-given graph.
Effect of Temperature on Resistance of Semiconductor
The material that offers moderate resistance is semiconductors. Examples are germanium, silicon. The semiconductor material has a negative temperature coefficient of resistance. The resistance of the semiconductor substances decreases with an increase in temperature. The resistivity of the semiconductor decrease exponentially with an increase in temperature as shown in the below-given graph.
Effect of Temperature on Resistance of Insulator
The materials which offer very high resistance and restrict the flow of electrons are called insulating materials. The insulating material has widespread use in electrical applications for preventing leakage current. Examples of insulating materials are- rubber, paper, glass, wood, plastic, mica, porcelain, polyester, SF6, mineral oil, nitrogen gas, etc.
Thus, the resistance of the semiconductor and insulator decrease with an increase in temperature.