What will be the effect of temperature on electrical conductivity of metallic conductors and semi-conductors ?

Explanation

### Step-by-Step Solution

1. **Understanding Electrical Conductivity**:
- Electrical conductivity is the ability of a material to conduct electric current. It is influenced by the movement of charge carriers (electrons and holes).

2. **Effect of Temperature on Metallic Conductors**:
- In metallic conductors, such as copper and aluminum, the electrical conductivity decreases with an increase in temperature.
- **Reason**: As temperature rises, the positive ions in the metal lattice vibrate more vigorously. This increased vibration creates more collisions between the conduction electrons and the vibrating ions, leading to increased resistance and thus decreased conductivity.

3. **Effect of Temperature on Semiconductors**:
- In semiconductors, such as silicon and germanium, the electrical conductivity increases with an increase in temperature.
- **Reason**: At higher temperatures, more electrons gain enough energy to jump from the valence band to the conduction band. This increase in charge carriers (free electrons) enhances the conductivity of the semiconductor.

4. **Conclusion**:
- Therefore, we conclude that:
- For metallic conductors: **Conductivity decreases with increasing temperature**.
- For semiconductors: **Conductivity increases with increasing temperature**.