Question

Resistivity of a wire is proportional to

• A. Relaxation time
• B. Area
• C. Length
• D. Temperature

Hint:

Resistivity is influenced by factors such as temperature and material properties, including electron density and relaxation time, which determine how easily electrons move through the material.

Answer 1

The Correct Option is A

The resistivity \( \rho \) of a material is given by the formula: \[ \rho = m \cdot \tau / n e^2 \] where: - \( m \) is the mass of an electron, - \( \tau \) is the relaxation time (the time between collisions of electrons), - \( n \) is the number density of electrons, - \( e \) is the charge of an electron. From the equation, it is clear that resistivity is directly proportional to the relaxation time. Thus, the correct answer is Relaxation time.