Class 12 Electric Charges And Fields CBSE Questions & Answers

When a negatively charged conductor is connected to earth,

An uncharged sphere of metal is placed inside a charged parallel plate capacitor. The lines of force look like

A hollow spherical conductor of radius 2m carries a charge of 500 \(\mu \) C. Then electric field strength at its surface is

A tennis ball which has been covered with charges is suspended by a thread so that it hangs between two metal plates. One plate is earthed, while other is attracted to a high voltage generator. The ball

A metallic solid sphere is placed in a uniform electric field. In the figure, which path will the lines of force follow?

Eight dipoles of charges of magnitude e are placed inside a cube. The total electric flux coming out of the cube will be

A charge q is placed at the center of the line joining two equal charges Q. The system of the three charges will be in equilibrium if q is equal to

Four point charges \({\rm{qA }} = {\rm{ 2 }}\mu {\rm{C}},{\rm{ qB }} = {\rm{ }}-{\rm{5 }}\mu {\rm{C}},{\rm{ qC }} = {\rm{ 2 }}\mu {\rm{C}},{\rm{ and qD }} = {\rm{ }}-{\rm{5 }}\mu {\rm{C}}\) are located at the corners of a square ABCD of side 10 cm. Force on a charge of \({\rm{1 }}\mu {\rm{C}}\) placed at the centre of the square is

A system has two charges \({{\rm{q}}_{\rm{A}}} = {\rm{ 2}}.{\rm{5 }} \times {\rm{ 1}}{0^{-{\rm{7}}}}{\rm{C}}\) and \({{\rm{q}}_{\rm{B}}} = {\rm{ }}-{\rm{2}}.{\rm{5 }} \times {\rm{ 1}}{0^{-{\rm{7}}}}{\rm{C}}\) located at points A: (0, 0, –15 cm) and B: (0,0, +15 cm), respectively. What are the total charge and electric dipole moment of the system?

An electric dipole with dipole moment \({\rm{4 }} \times {\rm{ 1}}{0^{-{\rm{9}}}}{\rm{C}}\) m is aligned at \({\rm{3}}0^\circ \) with the direction of a uniform electric field of magnitude \({\rm{5 }} \times {\rm{ 1}}{0^{\rm{4}}}{\rm{NC}}-{\rm{1}}\). Calculate the magnitude of the torque acting on the dipole.

Two insulated charged copper spheres A and B have their centres separated by a distance of 50 cm. What is the mutual force of electrostatic repulsion if the charge on each is \({\rm{6}}.{\rm{5 }} \times {\rm{ 1}}{0^{-{\rm{7}}}}{\rm{C}}\)? The radii of A and B are negligible compared to the distance of separation.

Two insulated charged copper spheres A and B have their centres separated by a distance of 50 cm and have identical sizes. A third sphere of the same size but uncharged is brought in contact with the first, then brought in contact with the second, and finally removed from both. What is the new force of repulsion between A and B?

Consider a uniform electric field \({\rm{E }} = {\rm{ 3 }} \times {\rm{ 1}}{0^{\rm{3}}}{\rm{N}}/{\rm{C}}\). (a) What is the flux of this field through a square of 10 cm on a side whose plane is parallel to the yz plane? (b) What is the flux through the same square if the normal to its plane makes a \({\rm{6}}0^\circ \) angle with the x-axis?

Careful measurement of the electric field at the surface of a black box indicates that the net outward flux through the surface of the box is \({\rm{8}}.0{\rm{ }} \times {\rm{ 1}}{0^{\rm{3}}}{\rm{N}}{{\rm{m}}^{\rm{2}}}/{\rm{C}}\). (a) What is the net charge inside the box? (b) If the net outward flux through the surface of the box were zero, could you conclude that there were no charges inside the box?

A point charge +10 \(\mu {\rm{C}}\) is a distance 5 cm directly above the centre of a square of side 10 cm, as shown in Figure. What is the magnitude of the electric flux through the square?