Page 1 : 1.10 Effect of Temperature on Resistance, , The resistance of the material increases as temperature of a metal increases. Let us see, the physical phenomenon involved in this process., , Atomic structure theory says that under normal temperature when the metal is, subjected to potential difference, ions i.e. unmovable charged particles get formed inside, the metal. The electrons which are moving randomly, get aligned in a particular direction, as shown in the Fig. 1.6., , Newel At low temperatures, the ions, vibrations are almost stationary. But as, , temperature increases, the ions, , — — gain energy and start oscillating, , about their mean position. Higher, , Free the temperature, greater is the, , + D+ Os Oa HC409 amplitude. Such vibrating ions, , cause obstruction to the flowing, , ton electrons. Similarly due to high, , 9-7 amplitude of oscillating ions,, , chances of collision of electrons, , are more. Due to collision and, , obstruction due to higher, , amplitude of oscillations of ions, the resistance of material increases as temperature, increases., , But this is not true for all materials. In some cases, the resistance decreases as, temperature increases., ¥3, , Fig. 1.6 Vibrating tons in a conductor, , , , Let us see the effect of temperature on resistance of various category of materials., , 1.10.1 Effect of Temperature on Metals, , The resistance of all the pure metals like copper, iron, tungsten etc. increases linearly, with temperature. For a copper, its resistance is 100 Q at 0° then it increases linearily, , Resistance in, , , , ‘Temperature, °c, , 2345 0 100, Fig. 1.7 Effect of temperature on metals, , Downloaded From : www.EasyEngineering.net