Identify the INCORRECT statement from the options given below.

Question

Question

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Delhi Police Head Constable (AWO/TPO) Official Paper (Held On : 27 Oct 2022 Shift 1)

Metals and their alloys have very large conductivity and are known as conductors.
Substances like glass, ceramics, etc., having very low conductivity are known as insulators.
Electrical conductance through metals is called metallic or electronic conductance and is due to the movement of electrons.
Certain materials called semiconductors by definition have zero resistivity or infinite conductivity.

Answer 1

The correct answer is Option 4.

Key Points

Option 4 states that "Certain materials called semiconductors by definition have zero resistivity or infinite conductivity," which is incorrect.
Semiconductors have a moderate level of conductivity, which is between that of insulators and conductors.
Semiconductors like silicon and germanium do not have zero resistivity; their resistivity decreases with increasing temperature.
In semiconductors, conductivity can be controlled by adding impurities, a process known as doping.

Additional Information

Conductors
- Materials that allow the flow of electric current with minimal resistance.
- Examples include metals like copper, silver, and aluminum.
Insulators
- Substances with very low conductivity, preventing the flow of electric current.
- Examples include glass, ceramics, and plastics.
Semiconductors
- Materials with conductivity between conductors and insulators.
- Used in electronic devices like transistors and diodes.
- Examples include silicon and germanium.
Doping
- The process of adding impurities to semiconductors to change their electrical properties.
- Increases the number of charge carriers in the material.