A point charge q is placed in a cavity in a metal block. If a charge Q is brought outside the metal, will the charge q feel an electric force?

A metallic sphere having no net charge is placed near a finite metal plate carrying a positive charge. The electric force on the sphere will be

A point charge +q is placed at the midpoint of a cube of side l. the electric flux emerging from the cube is

A thin. Metallic spherical shell contains s charge Q on it. A point charge q is placed at the centre of the shell and another charge q_1 is placed outside it as shown in figure (30-Q1). All the three charges are positive. The force on the charge at the centre is

Consider a point charge +q placed at the origin and another point charge -2p placed at a distance of 9 m from the charge +q . Determine the point between the two charges at which electric potential is zero.

A point charge q is placed at the midpoint of a cube of side L. The electric flux emerging from the cube is

The centre of mass is defined as vecR=1/Msum_im_ivecr_i . Suppose we define centre of charge as vecR_c=1/Qsum_iq_Ivecr_i where q_i represents the ith charge placed at vecr_i and Q is the total charge of the sytem a. Can a centre of charge of two charge system be outside the line segment joining the charges? b. If all the charges of a system are in X-Y plane? c. If all the charges of a system lie in a cube, is it necessary that the centre of charge be in the cube?