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3. current electricity — Physics STD 12 Science — Question

CBSE BoardEnglish MediumSTD 12 SciencePhysics3. current electricity1 Mark
MCQ
Suppose a current carrying wire has a cross-sectional area that, gradually become smaller along the wire, has the shape of a very long cone as shown in figure. Choose the correct statement
  • A
    Electric current is different in different portions of wire
  • B
    Electric field at point $A$ is same as that of point $B$
  • ✓
    Drift speed of electrons at point $A$ is lesser than that of at point $B$
  • D
    Drift speed of electrons at point $A$ is same as that of at point $B$
✓

Answer

Correct option: C.
Drift speed of electrons at point $A$ is lesser than that of at point $B$
c
$\mathrm{I}=\mathrm{neAV}_{\mathrm{d}}$

$\mathrm{I}=$ constant

$\mathrm{V}_{\mathrm{d}} \propto \frac{1}{\mathrm{A}}$

$\left(\mathrm{V}_{\mathrm{d}}\right)_{\mathrm{B}}>\left(\mathrm{V}_{\mathrm{d}}\right)_{\mathrm{A}}$

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