Current Electricity — Physics STD 12 Science — Question
Gujarat BoardEnglish MediumSTD 12 SciencePhysicsCurrent Electricity2 Marks
Question
Write relation between conductivity and mobility of metal.
✓
Answer
Ratio of drift velocity and electric field inside the conductor is constant at a given temperature. This constant quantity is known as mobility ( $\mu$ ) of charge carrier (electron) Mobility $(\mu)=\frac{\text { Drift velocity }}{\text { Electric field }}$ $=\frac{v_d}{ E }=\frac{\left(\frac{e E }{m}\right) \tau}{ E }=\frac{e \tau}{m}$ $\mu=\frac{e \tau}{m}$ Conductivity of the substance $\sigma=\frac{n e^2 \tau}{m}$ $\sigma=n e\left[\frac{e \tau}{m}\right]$ On putting the value from equation (1) in (2) $\sigma=n e(\mu)$ Hence, conductivity of metal $\sigma=n e \mu $
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