Resistance of Pure Metals

The resistance of pure metals is affected by various factors such as temperature, pressure, and impurities. Among these, temperature is the most significant factor that affects the resistance of pure metals.

Effect of Temperature on Resistance

When the temperature of a pure metal increases, the resistance of the metal also increases. This phenomenon is known as positive temperature coefficient of resistance. The following points explain why the resistance of pure metals increases with an increase in temperature:

- Increased Vibrations: As the temperature of the metal increases, the atoms of the metal vibrate more vigorously. This increased vibration leads to an increase in the resistance of the metal.

- Increased Collisions: The electrons in the metal collide with the atoms of the metal as they move through the metal. As the temperature of the metal increases, the number of collisions between the electrons and the atoms also increases. These collisions cause the resistance of the metal to increase.

- Decreased Mean Free Path: The mean free path of electrons is defined as the average distance that an electron travels between two consecutive collisions. As the temperature of the metal increases, the mean free path of electrons decreases. This decrease in mean free path leads to an increase in resistance.

- Increased Energy: The increase in temperature provides more energy to the electrons, which leads to an increase in their kinetic energy. This increased energy causes the electrons to move more freely, which in turn leads to an increase in resistance.

Conclusion

In conclusion, the resistance of pure metals increases with an increase in temperature due to increased vibrations, increased collisions, decreased mean free path, and increased energy. This phenomenon is known as positive temperature coefficient of resistance.