Questions in Electrostatics

Select	Question
	A sphere of radius $1\,cm$ has potential of $8000\,V$, then energy density near its surface will be
	Point charges $+ 4q,\, - q$ and $+ 4q$ are kept on the $x - $ axis at points $x = 0,\,x = a$ and $x = 2a$ respectively, then
	Two point charges of $20\,\mu \,C$ and $80\,\mu \,C$ are $10\,cm$ apart. Where will the electric field strength be zero on the line joining the charges from $20\,\mu \,C$ charge
	How much kinetic energy will be gained by an $\alpha - $ particle in going from a point at $70\,V$ to another point at $50\,V$
	If a charged spherical conductor of radius $10\,cm$ has potential $V$ at a point distant $5\,cm$ from its centre, then the potential at a point distant $15\,cm$ from the centre will be
	Two unlike charges of magnitude $q$ are separated by a distance $2d$. The potential at a point midway between them is
	What is the potential energy of the equal positive point charges of $1\mu C$each held 1 m apart in air
	An oil drop having charge $2e$ is kept stationary between two parallel horizontal plates 2.0 cm apart when a potential difference of 12000 volts is applied between them. If the density of oil is $900 kg/m^3$, the radius of the drop will be
	The ratio of momenta of an electron and an $\alpha$ -particle which are accelerated from rest by a potential difference of 100 volt is
	A proton is accelerated through 50,000 V. Its energy will increase by