Statement I : The electrical conductivity of a metal decreases as temp...
(b)
Increase in temperature causes thermal agitation of metal ions and thus, electrical conductivity is decreased. Thus, Statement I is correct. In the presence of electric field, flow of electrons is impeded. Thus, Statement II is correct but is not the correct explanation of Statement I.
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Statement I : The electrical conductivity of a metal decreases as temp...
Statement I
The electrical conductivity of a metal decreases as temperature increases.
Statement II
This impedes the flow of electrons when an electric field is applied.
Explanation:
Both Statement I and Statement II are correct, but Statement II is not the correct explanation of Statement I.
Explanation of Statement I:
The electrical conductivity of a metal is a measure of its ability to conduct electric current. In metals, the electrical conductivity is primarily due to the presence of free electrons that are delocalized and can move freely within the metal lattice. These free electrons are responsible for the flow of electric current.
As the temperature of a metal increases, the thermal energy also increases. This leads to an increase in the amplitude of lattice vibrations within the metal. These lattice vibrations can scatter the free electrons, causing them to collide with the lattice ions more frequently. These collisions hinder the flow of electrons and result in an increase in electrical resistance. Consequently, the electrical conductivity of the metal decreases as temperature increases.
Explanation of Statement II:
When an electric field is applied to a metal, the free electrons experience a force and start to move in a particular direction. However, as mentioned in Statement I, the increase in temperature leads to an increase in lattice vibrations and collisions between free electrons and lattice ions. These collisions impede the flow of electrons, opposing the motion caused by the electric field. As a result, the flow of electrons is hindered, and the electrical conductivity decreases.
Conclusion:
Both Statement I and Statement II are correct. The increase in temperature leads to an increase in lattice vibrations and collisions, which hinders the flow of electrons, reducing the electrical conductivity of the metal. However, Statement II is not the correct explanation of Statement I because it only describes the effect of temperature on the flow of electrons under an electric field, without directly explaining the relationship between temperature and electrical conductivity.