Download App

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

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

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

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "M.C.Q (1 Marks)" from 3. current electricity→3. current electricity — all question types→Physics STD 12 Science question papers→CBSE Board STD 12 Science question papers→CBSE Board question paper generator→

Similar questions

A resistance of $2 \Omega$ is comnected across one gap of a metre-bridge (the length of the wire is $100 \mathrm{~cm}$ ) and an unknown resistance, greater than $2 \Omega$, is connected across the other gap. When these resistance are interchanged, the balance point shifts by $20 \mathrm{~cm}$. Neglecting any corrections, the unknown resistance is
→
A coil of self-inductance $L$ is connected in series with a bulb $B$ and an $AC$ source. Brightness of the bulb decreases when:
→
A current carrying long solenoid is placed on the ground with its axis vertical. A proton is falling along the axis of the solenoid with a velocity $v$. When the proton enters into the solenoid, it will
→
Radiation of two photon energies twice and five times the work function of metal are incident sucessively on the metal surface. The ratio of the maximum velocity of photoelectrons emitted is the two cases will be
→
If the distance between H and Cl in HCl molecule is 1.28 A, then the value of electric dipole moment of this molecule will be (in Coulomb-meter):
→
A conductor in the form of a right angle $ABC$ with $AB = 3\, cm$ and $BC = 4\, cm$ carries a current of $10\, A$. There is a uniform magnetic field of $5\, T$ perpendicular to the plane of the conductor. The force on the conductor will be......$N$
→
In the given circuit the input voltage $V _{\text {in }}$ is shown in figure. The cut-in voltage of $p - n$ junction diode ( $D_{1}$ or $D_{2}$ ) is $0.6\,V$. Which of the following output voltage $\left( V _{0}\right)$ waveform across the diode is correct?
→
The path of difference between two interfering waves at a point on the screen is $\frac{\lambda}{8}$. The ratio of intensity at this point and that at the central fringe will be 
→
A student is provided with a variable voltage source $V$, a test resistor $R_T=10\,\Omega$, two identical galvanometers $G_1$ and $G_2$ and two additional resistors, $R _1=10\,M\,\Omega$ and $R _2=0.001\,\Omega$. For conducting an experiment to verify ohms law, the most suitable circuit is:
→
The charge flowing through a resistance $R$ varies with time as $Q = 2t - 8t^2$. The total heat produced in the resistance is (for $0 \leq t \leq \frac{1}{8}$)
→