AIIMS 2019 Physics Conductivity and Resistivity MCQ Question
Assertion : For a conductor resistivity increase with increase in temperature.
Reason : Since , when temperature increases the random motion of free electrons increases and vibration of ions increase which decrease
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
Correct Answer
Detailed Explanation
When temperature increases, the random motion of electrons and vibrations of ions intensifies, leading to more frequent collisions between electrons and ions. This results in a decrease in the average time between successive collisions (τ), which in turn increases the conductivity (σ) of the material, as conductivity is inversely related to resistivity (ρ). Consequently, resistivity increases (option B) and conductivity decreases (option C) are incorrect, as higher temperatures typically enhance electron mobility, thereby increasing conductivity. Option D is also incorrect since resistivity is expected to rise with temperature in conductive materials.
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