Classification of Metals, Conductors, and Semiconductors
Classification of Metals, Conductors, and Semiconductors
1. Introduction
Materials are classified based on their electrical conductivity into three main categories:
- Metals (Conductors)
- Semiconductors
- Insulators
The ability of a material to conduct electricity depends on the availability of free electrons and the
band structure of the material.
2. Conductors (Metals)
Definition:
Conductors are materials that allow electric current to pass through them easily due to the presence
of free electrons.
Properties of Conductors:
1. High Electrical Conductivity - They have very low electrical resistance.
2. Large Number of Free Electrons - The conduction band is partially filled or overlaps with the
valence band.
3. Low Resistivity (rho) - In the range of 10^-8 to 10^-6 Ohmm.
4. Ohm's Law Obedience - They follow Ohm's Law: V = IR.
5. Temperature Effect - Their resistance increases with temperature.
6. Examples - Copper, Silver, Gold, Aluminum, Iron.
Why Do Metals Conduct Electricity?
In metals, the valence band and conduction band overlap, allowing electrons to move freely, making
them excellent conductors.
3. Semiconductors
Definition:
Semiconductors are materials whose electrical conductivity lies between conductors and insulators.
Their conductivity can be controlled by external factors like temperature and doping.
Classification of Metals, Conductors, and Semiconductors
1. Introduction
Materials are classified based on their electrical conductivity into three main categories:
- Metals (Conductors)
- Semiconductors
- Insulators
The ability of a material to conduct electricity depends on the availability of free electrons and the
band structure of the material.
2. Conductors (Metals)
Definition:
Conductors are materials that allow electric current to pass through them easily due to the presence
of free electrons.
Properties of Conductors:
1. High Electrical Conductivity - They have very low electrical resistance.
2. Large Number of Free Electrons - The conduction band is partially filled or overlaps with the
valence band.
3. Low Resistivity (rho) - In the range of 10^-8 to 10^-6 Ohmm.
4. Ohm's Law Obedience - They follow Ohm's Law: V = IR.
5. Temperature Effect - Their resistance increases with temperature.
6. Examples - Copper, Silver, Gold, Aluminum, Iron.
Why Do Metals Conduct Electricity?
In metals, the valence band and conduction band overlap, allowing electrons to move freely, making
them excellent conductors.
3. Semiconductors
Definition:
Semiconductors are materials whose electrical conductivity lies between conductors and insulators.
Their conductivity can be controlled by external factors like temperature and doping.
