Assertion : A deuteron and an $\alpha -$ particle are placed in an electric field. If $F_1$ and $F_2$ be the forces acting on them and $a_1$ and $a_2$ be their accelerations respectively then, $a_1 = a_2$.

Reason : Forces will be same in electric field

Two identical conducing spheres having unequal positive charges $q_1$ and $q_2$ separated by distance $r$. If they are made to touch each other and then separated again to the same distance. The electrostatic force between the spheres in this case will be (neglect induction of charges)

Identify the wrong statement in the following. Coulomb's law correctly describes the electric force that

As shown in the figure. a configuration of two equal point charges $\left( q _0=+2 \mu C \right)$ is placed on an inclined plane. Mass of each point charge is $20\,g$. Assume that there is no friction between charge and plane. For the system of two point charges to be in equilibrium (at rest) the height $h = x \times 10^{-3}\,m$ The value of $x$ is $..........$.(Take $\left.\frac{1}{4 \pi \varepsilon_0}=9 \times 10^9\,Nm ^2 C ^{-2}, g=10\,ms ^{-1}\right)$

In hydrogen like system the ratio of coulombian force and gravitational force between an electron and a proton is in the order of:

Two free point charges $+q$ and $+4q$ are a distance $R$ apart. $A$ third charge is so  placed that the entire system is in equilibrium. Then the third charge is :-