A student makes the following statements about metals, insulators, and semiconductors - Scottish Highers Physics - Question 23 - 2023
Question 23
A student makes the following statements about metals, insulators, and semiconductors.
I In some metals, the valence and conduction bands overlap and each band is p... show full transcript
Worked Solution & Example Answer:A student makes the following statements about metals, insulators, and semiconductors - Scottish Highers Physics - Question 23 - 2023
Step 1
I In some metals, the valence and conduction bands overlap and each band is partially filled.
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Answer
This statement is correct. In certain metals, the conduction band overlaps with the valence band, allowing for the free movement of electrons.
Step 2
II The band gap between the valence band and the conduction band in an insulator is large compared to the band gap in a semiconductor.
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Answer
This statement is correct. Insulators typically have a large band gap (often greater than 4 eV), while semiconductors have a much smaller band gap (around 1 eV), which allows for easier excitation of electrons at room temperature.
Step 3
III An increase in temperature decreases the conductivity of a semiconductor.
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Answer
This statement is incorrect. An increase in temperature actually increases the conductivity of a semiconductor, as more electrons gain sufficient energy to jump from the valence band to the conduction band.
Step 4
Conclusion
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Answer
Given that statements I and II are correct, while III is not, the answer is C: I and II only.
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