Suppose the charge of a proton and an electron differ slightly. One of them is $- e,$ the other is $(e + \Delta e).$ If the net of electrostatic force and gravitational force between two hydrogen atoms placed at a distance $d$ (much greater than atomic size) apart is zero, then $\Delta e$ is of the order of [Given mass of hydrogen ${m_h} = 1.67 imes {10^{ - 27}}{\rm{kg}}$ ]

A body has a charge of $9.6 imes {10^{ - 20}}$ Coulomb. It is

Two metallic spheres of radii $1\;cm$ and $2cm$ are given charges ${10^{ - 2}}\;C$ and $5 imes {10^{ - 2}}C$ respectively. If they are connected by a conducting wire, the final charge on the smaller sphere is

One metallic sphere $A$ is given positive charge whereas another identical sphere $B$ of exactly same mass as of $A$ is given equal amount of negative charge. Then

The ratio of electrostatic and gravitational forces acting between electron and proton separated by a distance $5 imes {10^{ - 11}}m,$ will be (Charge on electron $= 1.6 imes {10^{ - 19}}C,$ mass of electron $= 9.1 imes {10^{ - 31}}kg,$ mass of proton $= 1.6 imes {10^{ - 27}}kg,\;G = 6.7 imes {10^{ - 11}}N{m^2}/k{g^2}$)

$ABC$ is a right angled triangle in which $AB = 3cm$ and $BC = 4cm.$ And $\angle ABC = \pi /2.$ The three charges $+ 15, + 12$ and $- 20{\rm{\;}}e.s.u$ are placed respectively on $A,B$ and $C.$ The force acing on $B$ is

Two identical charged spheres are suspended by strings of equal lengths. The strings make an angle of $30^\circ$ with each other. When suspended in a liquid of density $0.8\;{\rm{gc}}{{\rm{m}}^{ - 3}}$ , then angle remains the same. If density of the material of the sphere is $1.6\;{\rm{g c}}{{\rm{m}}^{ - 3}},$ the dielectric constant of the liquid is

Two point charges $q_1$ and $q_2$ are placed a distance $r$ apart in a medium with permittivity $\epsilon$. If a thin uncharged metallic spherical shell of radius $R < r/2$ is placed concentrically around $q_1$, what is the new force between the charges?

If charge $q$ is placed at the centre of the line joining two equal charges $Q$, the system of these charges will be the same distance would be

What is the total charge in coulomb of 75.0 kg of electrons?

Two point charges repel each other with a force of 100 N. One of the charges is increased by 10% and other is reduced by 10%. The new force of repulsion at the same distance would be