Three point charges +q, $$-$$ 2q and + q are placed at points (x = 0, y = a, z = 0), (x = 0, y = 0, z = 0) and (x = $$a$$, y = 0, z = 0) respectively. The magnitude and direction of the electric dipole moment vector of this charge assembly are

An electric dipole of moment $$\overrightarrow p $$ is lying along a uniform electric field $$\overrightarrow E $$. The work done in rotating the dipole by 90^o is

A square surface of side L metres is in the plane of the paper. A uniform electric field $$\overrightarrow E $$ (volt/m), also in the plane of the paper is limited only to the lower half of the square surface (see figure). The electric flux in SI inits associated with the surface is

Two charges q₁ and q₂ are placed 30 cm apart, as shown in the figure. A third charge q₃ is moved along the arc of a circle of radius 40 cm from C to D.

The change in the potential energy of the system is $${{{q_3}} \over {4\pi {\varepsilon _0}}}$$ where k is