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XII Class
(20022-2023)
Unit Test – 1
Physics
20 Marks

SET – A

  1. Name the physical quantity whose S.I. unit is N/C. Is it a scalar or vector quantity? (1M)
  2. Calculate the electric flux through a cube of side 2 cm which encloses an electric dipole. (1M)
  3. Plot a graph showing variation of electric field as a function of r>R and r<R ( r being the distance from the centre of the shell and R is radius of the shell) (1M)
  4. Why electric field lines are always normal to the surface of a conductor on which the charges are in equilibrium. (1M)
  5. Draw the electric field lines for (i) Q>0 and (ii) Q<0 (1 M)
  6. Two point charges +4 μC and +1 μC are separated by a distance of 2 m in air. Find the point on the line-joining charges at which the net electric field of the system is zero. (2 M)
  7. In which orientation, a dipole placed in a uniform electric filed is in (i) stable, (ii) unstable equilibrium. (2 M)
  8. Consider two hollow concentric spheres, S1 and S2 (size of S1<S2), enclosing charges 2Q and 4Q respectively. Find the ratio of the electric flux through S1 and S2(that is Ф1:Ф2) (2 M)
  9. Derive an expression for the torque on an electric dipole placed in a uniform electric field. What happens when an electric dipole placed in non-uniform electric field. (3 M)
  10. State “Gauss law” in electrostatics. Use this law to derive an expression for the electric field
    due to an infinitely long straight wire of linear charge density λ Cm-1. (3M)
  11. Define dipole moment. Derive an expression for the electric field at any point on the axial line of an electric dipole.

SET – B

  1. Name the physical quantity whose S.I. unit is NC-1m2. Is it a scalar or vector quantity? (1M)
  2. Calculate the electric flux through a cube of side 4 cm which encloses an electric dipole. (1M)
  3. Draw a graph to show the variation of “E” with perpendicular distance “r” from the line of charge (infinitely charged wire) (1M)
  4. Write any two properties of electric field lines. (1M)
  5. Draw the electric field pattern for two equal and positive point charges. (1M)
  6. Two point charges +1 μC and +4 μC are separated by a distance of 30 cm in air. Find the point on the line-joining charges at which the net electric field of the system is zero. (2 M)
  7. In which orientation, a dipole placed in a uniform electric filed is in (i) stable, (ii) unstable
    equilibrium. (2 M)
  8. Consider two hollow concentric spheres, S1 and S2 (size of S1<S2), enclosing charges 3Q and 6Q respectively. Find the ratio of the electric flux through S1 and S2 (that is Ф1:Ф2) (2 M)
  9. Derive an expression for the torque on an electric dipole placed in a uniform electric field. What happens when an electric dipole placed in non-uniform electric field. (3 M)
  10. State “Gauss law” in electrostatics. Use this law to derive an expression for the electric field due to an infinite plane sheet of charge. (3M)
  11. Define dipole moment. Derive an expression for the electric field at any point on the equatorial line of an electric dipole. (3 M)

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