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Physics - Current Electricity Question with Solution | TestHub

PhysicsCurrent ElectricityMicroscopicHard2 minPYQ_2021

PhysicsHardsingle choice

In the given figure, a battery of emf $E$ is connected across a conductor $P Q$ of length $l$ and different area of cross-sections having radii $r_{1}$ and $r_{2} (r_{2} < r_{1}) .$

Choose the correct option as one moves from $P$ to $Q$ .

Options:

Answer:

Solution:

Current is constant in conductor
$i =$ constant
Resistance of element $d R = \frac{ρ d x}{π r^{2}}$
$d V = i d R = \frac{ipdx}{π r^{2}}$
$E = \frac{d V}{d x} = \frac{i ρ}{π r^{2}}$
and $V_{d} = \frac{e E τ}{m}$
$∴ V_{d} \times E$

$\to E \propto \frac{1}{r^{2}}$

If $r$ decreases, $E$ will increase.

$∴ V_{d}$ will increase.

Stream:JEESubject:PhysicsTopic:Current ElectricitySubtopic:Microscopic

⏱ 2mℹ️ Source: PYQ_2021

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