Electric Charge...

A hollow conducting sphere has inner radii $$5\ cm$$ and outer radius $$8\ cm$$ then find maximum possible potential of conductor if breakdown electric field of air is $$3 \times 10^6 V/m$$

Two particle of equal mass $$m$$ and charge $$q$$ are placed at a distance of $$16$$ cm. They do not experience any force. The value of $$\dfrac { q }{ m } $$ is

Two charge particles $$+3 \mu C$$ and $$-2 \mu C$$ are placed 2 m apart. Half of the region between them is filled with a medium having relative permttivity 9. Find the electric force between two charges.

A charge Q is divide in two parts $$ Q_1 $$ and $$ Q_2 $$ and these charges are placed at a distance R. there will be maximum repulsion between them when.

A metallic ring is inserted through a sot iron cylinder which is wound with a copper wire and fixed to the wooden base as shown in the diagram when we flow A.C current through the copper wire then metal ring is leviated on the coil because,
Choose the correct option from above and give explanation

An infinite number of electric charges, each of magnitude $$1 \mu C$$, are placed on the x-axis with coordinates $$x=1,2,4,8...\infty$$ , If charge of 1 $$C$$ is kept at the origin. Calculate the net force acting on this charge.

The smiling face in figure consists of three items (a), A thin rod of charge $$-3.0\ \mu C$$ that forms a full a form circle of rading $$6\ cm$$.
(b) second thin rod of charge $$2.0\ \mu C$$ that forms a circular are of radius $$4.0\ cm$$. Subtending an angle of $$20^\circ$$ about the centre of the full circle and 
(c) Electric dipole with a dipole moment that is $$\perp$$ to a radial line and has a magnitude $$1.28 \times 10^{-21}\ cm$$, what is the net electric potential of the centre.

Electric force between two charged sphere is $$18$$ units. If the distance between the centres of the sphere sphere is tripled , the electric field will be

$$U ( x ) = \frac { c } { x ^ { 9 } } - \frac { d } { x }$$ ; where $$c$$ and $$d$$ are positive constants and $$x$$ is the distance between the atoms
Find the force $$F(x)$$ between the atoms.

Two charges placed in air at a distance 1 m exert force.'F' on each other. If these charges placed inside mica at same distance, then the new force between charges is