Class 12 Electric Charges And Fields CBSE Questions & Answers

Class 12 · Electric Charges And Fields

This is Physics Class 12 Electric Charges and Fields CBSE Questions & Answers. There are 15 questions in this test with each question having around four answer choices.

Questions & Answers

1
Electric field lines can be said to be
  • A
    lines of equal Electric field
  • B
    graphical representation of electric fields.
    Correct
  • C
    drawing lines of electric fields
  • D
    lines of equal Electric voltage
2
At any point on S on an electric field line
  • A
    the perpendicular to the line is in the direction of \(\vec{E}\) at that point
  • B
    the binormal to the line is in the direction of \(\vec{E}\)at that point
  • C
    the curvature is in the direction of \(\vec{E}\) at that point
  • D
    the tangent to the line is in the direction of \(\vec{E}\) at that point
    Correct
3
An electric dipole is
  • A
    a pair of electric charges of equal magnitude q but positive sign, separated by a distance d
  • B
    a pair of electric charges of equal magnitude q but opposite sign, separated by a distance
    Correct
  • C
    a pair of electric charges of equal magnitude q separated by a distance d
  • D
    a pair of electric charges of equal magnitude q but negative sign, separated by a distance d
4
The direction of an electric dipole
  • A
    is from negative to positive charge
    Correct
  • B
    is perpendicular to line from positive to negative charge
  • C
    is perpendicular to line from negative to positive charge
  • D
    is from positive to negative charge
5
Electric flux
  • A
    Is a measure of the electric power through a surface
  • B
    Is a measure of the area of electric field through a surface
  • C
    Is a measure of the electric field potential through a surface
  • D
    Is a measure of the "flow" (in analogy with flow of fluids) of electric field through a surface.
    Correct
6
Gauss's law states that
  • A
    the total electric field flux coming out of a closed surface equals the net charge enclosed within the volume divided by \({\varepsilon _0}\)
    Correct
  • B
    the total electric field flux coming out of a closed surface equals the charge enclosed within the volume divided by \({\varepsilon _0}\)
  • C
    the total electric field flux coming out of a closed surface equals the net charge enclosed within the volume
  • D
    the total electric field flux coming out of an open surface equals the net charge enclosed within the volume divided by \({\varepsilon _0}\)
7
An electric dipole in an electric field experiences a torque {tex}\vec \tau {tex}
  • A
    equal to the vector product of \(\vec p{tex} and {tex}\vec E\)
    Correct
  • B
    equal to the scalar product of \(\vec p{tex} and {tex}\vec E\)
  • C
    equal to the vector product of \(\vec E{tex} and {tex}\vec p\)
  • D
    equal to the scalar product of {tex}\vec E{tex} and {tex}\vec p{tex}
8
For a thin infinitely long straight wire of uniform linear charge density \(\lambda \) at a distance R from the wire The magnitude of \(\vec{E}\) is
  • A
    \(E =\frac{λ }{2\pi \epsilon_0 R}\). ${\text{Cos}}\theta $
    Correct
  • B
    B . \(E =\frac{λ }{4\pi \epsilon_0 R}\)
  • C
    \(E =\frac{λ }{3\pi \epsilon_0 R}\)
  • D
    \(E =\frac{λ^2 }{2\pi \epsilon_0 R}\)
9
For an Infinite thin plane sheet of uniform surface charge density \(\sigma {tex} The magnitude of {tex}\vec{E}\) is
  • A
    \(E =\frac{σ }{ \epsilon_0 }\)
  • B
    \(E =\frac{σ }{2 \epsilon_0 }\)3
    Correct
  • C
    A . \(E =\frac{σ^2 }{ \epsilon_0 }\)
  • D
    \(E =\frac{σ^2 }{2 \epsilon_0 }\)
10
For a thin spherical shell of uniform surface charge density \(\sigma \) , The magnitude of \(\vec{E}\) just outside is
  • A
    \(E =\frac{4\pi R^2 σ}{4\pi \epsilon_0 r^3}\)
  • B
    \(E =\frac{4\pi R^2 σ}{4\pi \epsilon_0 r^2}\)
    Correct
  • C
    A . \(E =\frac{R^2 σ}{4\pi \epsilon_0 r^2}\)
  • D
    \(E =\frac{4\pi R σ^2}{4\pi \epsilon_0 r^2}\)
11
An electric field can deflect
  • A
    X rays
  • B
    γ - rays
  • C
    Neutrons
  • D
    α – rays
    Correct
12
Which one of the following graphs represents the variation of electric field strength E with distance ‘r’ from the centre of a uniformly charged non conducting sphere?
  • A
    Image D Option A
  • B
    Image C Option B
    Correct
  • C
    Image A Option C
  • D
    Image B Option D
13
A conducting sphere of radius 5 cm is charged to 15 {tex}\mu {tex} C. Another uncharged sphere of radius 10 cm is allowed to touch it for enough time. After the two are separated, the surface density of charge on the two spheres will be in the ratio
  • A
    3:1
  • B
    1:2
  • C
    1:1
  • D
    2:1
    Correct
14
A Gaussian sphere encloses an electric dipole within it. Total flux across the sphere is
  • A
    half that due to a single charge
  • B
    Zero
    Correct
  • C
    dependent on position of the charge
  • D
    double that due to single charge
15
A cylinder of radius R and length L is placed in an uniform electric field E parallel to the cylinder axis. The total flux for the surface of the cylinder is given by
  • A
    $\pi {{\text{R}}^{\text{2}}}{\text{E}}$
  • B
    ${\text{2}}\pi {{\text{R}}^{\text{2}}}{\text{E}}$
  • C
    $\pi {{\text{R}}^{\text{2}}} + \pi {{\text{L}}^{\text{2}}}$
  • D
    0
    Correct