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Question
Draw the energy band diagrams for conductors, semiconductors and insulators. Which band determines the electrical conductivity of a solid? How is the electrical conductivity of a semiconductor affected with rise in its temperature? Explain.
Solution
Conduction band determines the conductivity of solids.
The gap between conduction band and valence band is small in semiconductors. Therefore, electrons, gaining energy, can jump from the valence band to the conduction band on increasing temperature. So, the conductivity of semiconductor increases with increase in temperature.
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