Quiz  /  Electric flux Class 12 MCQ Questions With Answers

  • 1. 
    The electric intensity due to an infinite cylinder of radius R and having charge q per unit length at a distance r (r>R) from its axis is

  • Directly proportional to r2r^2r2
  • Directly proportional to r
  • Inversely proportional to r
  • Inversely proportional to r2r^2r2

  • 2. 
    The S.I. unit of electric flux is

  • Joule per coulomb
  • Newton per coulomb
  • Weber
  • Volt metre

  • 3. 
    Fig. shown is a distribution of charges. The flux of electric field due to these charges through the surface S is

  • 3q∈0\frac{3q}{\in_0}∈0​3q​
  • q∈0\frac{q}{\in_0}∈0​q​
  • zero
  • 2q∈0\frac{2q}{\in_0}∈0​2q​

  • 4. 
    An electric dipole is put in north-south direction in a sphere filled with water. Which statement is correct

  • Electric flux is coming towards sphere
  • Electric flux is coming out of sphere
  • Electric flux entering into sphere and leaving the sphere are same
  • Water does not permit electric flux to enter into sphere

  • 5. 
    Two infinite plane parallel sheets separated by a distance 'd' have equal and opposite uniform charge densities σ\sigmaσ . Electric field at a point between the sheets is

  • Zero
  • σ2∈0\frac{\sigma}{2\in_0}2∈0​σ​
  • Depends upon the location of the point
  • σ∈0\frac{\sigma}{\in_0}∈0​σ​

  • 6. 
    The dimensional formula of electric charge is

  • M0L0T1A1M^0L^0T^1A^1M0L0T1A1
  • M0L0T−1A1M^0L^0T^{-1}A^1M0L0T−1A1
  • M0L0T1A−1M^0L^0T^1A^{-1}M0L0T1A−1
  • M0L0T−1A−1M^0L^0T^{-1}A^{-1}M0L0T−1A−1

  • 7. 
    Which line, A to D, gives correct units for both magnetic flux and magnetic flux density?

  • A
  • B
  • C
  • D

  • 8. 
    If the net flux through a gaussian surface is zero, the following four statements could be true. Which of the statements must be true?(a) There are no charges inside the surface. (b) The net charge inside thesurface is zero. (c) The electric field is zero everywhere on the surface.(d) The number of electric field lines entering the surface equals the number leaving the surface.

  • There are no charges inside the surface.
  • The net charge inside the surface is zero.
  • The electric field is zero everywhere on the surface.
  • The number of electric field lines entering the surface equals the number leaving the surface.

  • 9. 
    If I triple the value of charge of a test charge the electric field will

  • Increase by 3
  • Increase by 9
  • Not change
  • Decrease by 9

  • 10. 
    The magnitude of the e.m.f. induced in a conductor is proportional to

  • the change in the flux
  • the rate of change of flux
  • the change in the field strength
  • the rate of change of field strength

  • 11. 
    Three charges, each of value Q, are placed at the vertex of an equilateral triangle. A fourth charge q is placed at the centre of the triangle. If the charges remains stationery then, q = ______

  • Q/√2Q/√2Q/√2
  • −Q/√3-Q/√3−Q/√3
  • −Q/√2-Q/√2−Q/√2
  • Q/√3Q/√3Q/√3

  • 12. 
    What quantity remains the same everywhere between two parallel plates?

  • Electric Field
  • Electric Potential
  • Electric Potential Energy
  • Speed

  • 13. 
    In the generator shown a coil rotates inside a magnetic field. Which of these factors will not affect the peak e.m.f. of the output of the generator?

  • The direction of rotation of the coil
  • The strength of the magnetic field
  • The length of the wire coil inside the field
  • The frequency of rotation

  • 14. 
    Suppose a point charge is located at the center of a spherical surface. The electric field at the surface of the sphere and the total flux through the sphere are determined. Now the radius of the sphere is halved. What happens to the flux through the sphere and the magnitude of the electric field at the surface of the sphere?

  • The flux and field both increase.
  • The flux and field both decrease.
  • The flux increases, and the field decreases.
  • The flux decreases, and the field increases.
  • The flux remains the same, and the field increases.

  • 15. 
    Electric flux is maximum at angle

  • 45
  • 90
  • 180
  • 0

  • 16. 
    How do electric field lines represent the magnitude of an electric field?

  • Length of the line
  • With arrows
  • Density of lines
  • Width of lines

  • 17. 
    The diagram shows a long wire placed in a magnetic field directed out of the screen. Which on of these answers correctly describes the direction of the induced current in the wire when it is moved upwards, and to the right?

  • Moved upwards: Current to the rightMoved to the right: Current to the left
  • Moved upwards: No currentMoved to the right: Current to the right
  • Moved upwards: Current to the rightMoved to the right: No current
  • Moved upwards: Current to the leftMoved to the right: No current

  • 18. 
    There are several ways to induce an e.m.f. in a conductor. Which one of these will not work?

  • Move a wire around a magnet
  • Place a strong magnet next to a coil
  • Increase the strength of a magnetic field near a coil
  • Move a magnet in and out of a coil

  • 19. 
    The electric flux through the planar surface above ( positive unit normal to left ) is:

  • Positive
  • Negative
  • Zero

  • 20. 
    The intersection of field lines is due to

  • attraction
  • repulsion
  • it is not possible
  • both attraction and repulsion

  • 21. 
    Fringing of field lines is due to

  • Uniform electric field
  • Non uniform electric field
  • Uniform charges on plates
  • Non uniform charges on plates
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