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Questions and Answers
In a semiconductor, the Fermi level is situated at the middle of the valence band.
In a semiconductor, the Fermi level is situated at the middle of the valence band.
False
The forbidden band in a semiconductor has a width of 0.72 eV at room temperature.
The forbidden band in a semiconductor has a width of 0.72 eV at room temperature.
True
Copper is a p-type semiconductor.
Copper is a p-type semiconductor.
False
The number of free electrons in an intrinsic semiconductor is equal to the number of holes.
The number of free electrons in an intrinsic semiconductor is equal to the number of holes.
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The conductivity of a semiconductor increases with an increase in temperature.
The conductivity of a semiconductor increases with an increase in temperature.
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Study Notes
Introduction to Materials
- Solids can be classified into three main categories: conductors, insulators, and semiconductors based on their electrical conductivity.
- Conductors allow electric current to flow through them with minimal resistance, examples include copper, gold, and aluminum.
- Insulators resist the flow of electric current, examples include wood, glass, and rubber.
- Semiconductors have intermediate conductivity, and their electrical conductivity can be controlled, examples include silicon and germanium.
Atomic Structure and Electrical Conductivity
- The electrical conductivity of a material is determined by the arrangement of its electrons in the atomic structure.
- In conductors, the outermost energy level is not fully occupied, allowing electrons to move freely and conduct electricity.
- In insulators, the outermost energy level is fully occupied, preventing electrons from moving freely and conducting electricity.
- In semiconductors, the outermost energy level is partially occupied, allowing some electrons to move freely and conduct electricity under certain conditions.
Energy Bands and Electrical Conductivity
- The energy levels of electrons in a material can be represented by energy bands, which are ranges of energy levels.
- The valence band is the lowest energy band, where electrons are bound to the atom, and the conduction band is the highest energy band, where electrons are free to move.
- In conductors, the valence band and conduction band overlap, allowing electrons to move freely between the two bands.
- In insulators, the valence band and conduction band are separated by a large energy gap, preventing electrons from moving between the two bands.
- In semiconductors, the valence band and conduction band are separated by a small energy gap, allowing some electrons to move between the two bands under certain conditions.
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Description
This quiz covers the basics of materials, including their properties and classification as conductors, insulators, and semiconductors. Understand the differences between these materials and their applications.
