CBSE 2023 · Region 5 · Set 1 · Q24 · 2 marks
The potential difference applied across a given conductor is doubled. How will this affect (i) the mobility of electrons and (ii) the current density in the conductor? Justify your answers.
Marking-scheme solution
(i) Effect of potential difference on mobility of electron \(\displaystyle \left(\frac{1}{2}\right)\) Justification
(i) Effect of potential difference on current density
Justification
(i) No effect
\(\displaystyle \mu=\frac{\mathrm{v}_{d} l}{\mathrm{V}}=\frac{l}{\text { enAR }}=\) Constant
Alternatively: \(\displaystyle \mu=\frac{\mathrm{v}_{d}}{E}=\frac{e \tau}{m}=\) Constant(ii) As \(\displaystyle \mathrm{J} \alpha \mathrm{V}\), current density gets doubled
\[\mathrm{J}=\frac{I}{A}=\frac{\mathrm{V}}{R A}
\]
Current ElectricityDrift of Electrons and the Origin of ResistivityUnderstandvery_short_answermedium
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