Electric Charge...

Electric field at a distance $$4R$$ from the surface of a charge cylinder is $$E$$ . If $$R$$ is the radius of the cylinder and $$L$$ is the length of the cylinder then surface charge density of the cylinder is:

The net electric force on a charge of $$+3\mu C$$ at the mid-point on the line joining two charges of magnitude $$+2\mu C$$ and $$-2\mu C$$ separated by the distance of $$6\ mm$$, is

Two isolated charge metallic spheres of radii $$R_{1}$$ and $$R_{2}$$ having charge $$Q_{1}$$ and $$Q_{2}$$ respectively are connected to each other, then there is:

The electric field at point $$(30,30,0)cm$$ due to a charge of $$0.008\mu C$$ at origin will be _____

Two identical charged spheres suspended from a common point by two mass less strings of lengths l, are initially at a distance d apart because of  their mutual repulsion. the charges begin to leak from both the spheres at a constant rate. as a result, the spheres approach each other with the velocity v. then v varies as a function of distance x between the spheres , as

A square loop of side b is rotating with angular speed $$\omega$$ about one of the diagonals as axis. At $$t=0$$, the plane of the loop is perpendicular to the magnetic field B. If the number of turns of the loop be N then what is the instantaneous flux through the coil

The potential difference between two isolated spheres of radii $$r_{1}$$ and $$r_{2}$$ is zero. The ratio of their charges $$Q_{1}/Q_{2}$$ will be-

An elementary particle of mass $$m$$ and charge $$+e$$ is projected with velocity $$v$$ at a much more massive particle of charge $$Ze$$, where $$Z>0$$. What is the closed possible approach of the incident particle?

Two charges each of $$2$$ micro coulomb are $$0.5\ m$$ apart. If both of them axis vacuum, them the force between them is

The force of attraction between two charges separated by certain distance in air is $$F_{1}$$. If the space between the charges is completely filled with dielectric of constant $$4$$ the force becomes $$F_{2}$$. If half of the distance between the charges is filled with same dielectric the force between the charges is $$F_{3}$$. Then $$F_{1} : F_{2} : F_{3}$$ is