Two identical point charges of magnitude –q are fixed as shown in the figure below. A third charge +q is placed midway between the two charges at the point P. Suppose this charge +q is displaced a small distance from the point P in the directions indicated by the arrows, in which direction(s) will +q be stable with respect to the displacement?

Two identical conducting balls having positive charges q₁ and q₂ are separated by a centre to centre distance r. If they are made to touch each other and then separated to the same distance, the force between them will be _____.

The relative permittivity of water is _______.

An uncharged metal sphere is placed between two equal and oppositely charged metal plates. The nature of lines of force will be ______________

Define ‘electric dipole’. Give the expression for the magnitiude of its electric dipole moment and the direction.

What are the properties of an equipotential surface?

What are Non-polar molecules? State examples.

What is the electric flux through a cube of side 1 cm which encloses on electric dipole?

A positive charge +q is located at a point, what is the work done, if a unit positive charge is carried once around this charge along a circle of radius r about this point?

Two small-sized identical equally charged spheres, each having mass 1 g are hanging in equilibrium as shown in the figure. The length of each string is 10 cm and the angle θ is 30° with the vertical. Calculate the magnitude of the charge in each sphere. (Take g = 10 ms⁻²)

Calculate the electric field at points P, Q for the following two cases, as shown in the figure.
(a) A positive point charge +1 μC is placed at the origin.
(b) A negative point charge -2 μC is placed at the origin.

A block of mass m carrying a positive charge q is placed on an insulated frictionless inclined plane as shown in the figure. A uniform electric field E is applied parallel to the inclined surface such that the block is at rest. Calculate the magnitude of the electric field E.

Write the special features of Gauss law.

What is dielectrics or insulators.

Four charges are arranged at the corners of the square PQRS of side an as shown in the figure.
(a) Find the work required to assemble these charges in the given configuration.
(b) Suppose a charge q is brought to the center of the square, by keeping the four charges fixed at the corners, how much extra work is required for this?

A water molecule has an electric dipole moment of 6.3 x 10^-30 Cm. A sample contains 10²² water molecules, with all the dipole moments aligned parallel to the external electric field of magnitude 3 x 10⁵ NC^-1. How much work is required to rotate all the water molecules from θ = 0° to 90°? 

Three points A, B & C lie in a uniform electric field (E) of 5 x 10³ NC^-1 Find the potential difference between A & C.

A polythene piece rubbed with wool is found to have a negative charge of 3 x 10^-7 C. Estimate the number of electrons transferred from which to which?