Electric Charge...

A charge of magnitude $$q$$ is divided into two parts such that force between resulting two charges is maximum when separated through some distance $$r$$. The division of charges would be

Five equal charges each of value $$q$$ are placed at the corners of a regular pentagon of side $$a$$. The electric field at the centre of the pentagon is:

A positive charge $$Q$$ is uniformly distributed along a circular ring of radius $$R$$. A small test charge $$q$$ is placed at the centre of the ring as shown in then figure. 

A rectangular surface of sides 10 cm and 15 cm is placed inside a uniform electric field of 25 V/m, such that the surface makes an angle $$30^{\circ}$$ with the direction of electric field. Find the flux of the electric field  through the rectangular surface 

When a point charge of $$\frac{1}{3}\mu C$$ is placed along the axis of a thin disc of total charge $$\frac{2}{3}\mu C$$ (uniform distribution) and radius 3.95 cm such that distance between the point charge and centre of disc is 1 m, then force experienced by disc is approximately:

In figure two positive charges, $${q}_{2}$$ and $${q}_{3}$$ fixed along the y-axis, exert a net electric force in the $$+x$$ direction on a charge $${q}_{1}$$ fixed along the x-axis. If a positive charge $$Q$$ is added at $$(x,0)$$, the force on $${q}_{1}$$:

Two charges $$+20\mu C$$ and $$-20\mu C$$ are placed $$10mm$$ apart. The electric field at point $$P$$, on the axis of the dipole $$10cm$$ away from its centre $$O$$ on the side of the positive charge is

A conducting sphere of radius $$10cm$$ has unknown charge. If the electric field at a distance $$20cm$$ from the centre of the sphere is $$1.2\times { 10 }^{ 3 }N { C }^{ -1 }$$ and points radially inwards. The net charge on the sphere is:

Two fixed point charges $$ + 16\mu C$$ and $$ - 9\mu C$$ are placed $$8cm$$ apart in air. Where should a third point charge placed so that, the third charge is in equilibrium

Two conducting and concentric thin spherical shells or radii $$a$$ and $$b,\,\left( {b > a} \right)$$ have charges $${q_1}$$ and $${q_2}$$ respectively. Now if the inner shell is earthed then the final charge on this shell will be