For a metallic conductor obeying Ohm law, if temperature increases

Question

Accepted Answer

C. {'text': 'Relaxation time τ decreases; therefore ρ increases', 'label': 'C'}

1. From v_d = -eEτ/m, drift velocity is directly proportional to relaxation time τ.
2. In metals, increased temperature makes lattice vibrations stronger, causing more electron-ion collisions.
3. Average time between collisions τ therefore decreases with temperature.
4. Since j = σE and σ = neτ e / m, decreasing τ decreases σ and increases ρ = 1/σ.
_Source: NCERT Class 12 Physics, Ch 3 "Current Electricity", §3.5_

Answer

{'text': 'Resistivity ρ decreases with temperature', 'label': 'A'}

Answer

{'text': 'Drift velocity increases with temperature at constant field', 'label': 'B'}

Answer

{'text': 'Conductivity σ increases with temperature', 'label': 'D'}