CBSE 2023 · Region 5 · Set 3 · Q24 · 2 marks
Two conductors, made of the same material have equal lengths but different cross-sectional areas $\displaystyle \mathrm{A}_{1}$ and $\displaystyle \mathrm{A}_{2}\left(\mathrm{~A}_{1}>\mathrm{A}_{2}\right)$. They are connected in parallel across a cell. Show that the drift velocities of electrons in two conductors are equal.
Marking-scheme solution
\[\begin{aligned}
I & =n e \mathrm{A} V d \\
\mathrm{v}_{d} & =\frac{I}{n e \mathrm{A}}=\frac{V \mathrm{A}}{n e \mathrm{A} \rho l} \\
\mathrm{v}_{d} & =\frac{V}{\rho \ln e}
\end{aligned}
\] In parallel drift velocity is independent of area cross section So drift velocities are same in both the conductors
Current ElectricityDrift of Electrons and the Origin of ResistivityApplyvery_short_answermedium
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