# Chapter 1 Electric Charges And Fields – Important Questions

Electric Charges and Fields Class 12 Physics Important Questions - 1 Mark Very Short Answer Type.

## Important Questions 1 mark

Answer : When dipole moment vector is parallel to electric field vector.

Answer: Electic flux ϕE is given by
ϕE=Eds =Q/ε0

where Q is total charge inside the closed surface.
∴ On changing the radius of sphere, the electric flux through the Gaussian surface remains same.

Answer :

• For stable equilibrium, a dipole is placed parallel to the electric field.
• For unstable equilibrium, a dipole is placed antiparallel to the electric field.

Answer:

• Physical quantity whose S.I. unit is JC-1 is Electric potential.
• It is a Scalar quantity.

Answer: Electric dipole moment of an electric dipole is defined as the product of the magnitude of either charge and dipole length.

Answer:
Electrostatic field inside a conductor should be zero because of the absence of charge. As in a static condition, charge remains only on the surface.

Answer : So that tangent on charged conductor gives the direction of the electric field at that point.

Answer : Electric flux through each phase of the cube.

Answer : Direction of the magnetic field lines is given by right hand thumb rule.

Answer:
The direction of electric field is normal and inward to the surface.

Answer:
Electric field lines do not form closed loops because the direction of an electric field is from positive to negative charge. So one can regard a line of force starting from a positive charge and ending on a negative charge. This indicates that electric field lines do not form closed loops.

Answer:
No, it is not necessarily zero. If the electric field due to a charge configuration with total charge is zero because the electric field due to an electric dipole is non-zero.

Answer:
The electric lines of force give the direction of the electric field. In case, two lines of force intersect, there will be two directions of the electric field at the point of intersection, which is not possible.

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