JEE Main · 2009 · 12 Apr 2009 · Offline · Electrostatics

Six point charges are kept 60° apart from each other on the circumference of a circle of radius R as shown in figure. The net electric field at the centre of the circle is ______.
(${ϵ}_0$ is permittivity of free space)

Electric field in a region is given by $\vec{E}=Ax\hat{i}+By\hat{j}$, where $A=10\mathrm{V}/{\mathrm{m}}^2$ and $B=5\mathrm{V}/{\mathrm{m}}^2$. If the electric potential at a point $(10,20)$ is 500 V , then the electric potential at origin is ____ V.

Three small identical bubbles of water having same charge on each coalesce to form a bigger bubble. Then the ratio of the potentials on one initial bubble and that on the resultant bigger bubble is :

Five positive charges each having charge $q$ are placed at the vertices of a pentagon as shown in the figure. The electric potential ($V$) and the electric field ($\vec{E}$) at the center O of the pentagon due to these five positive charges are:

Two point charges 2q and q are placed at vertex A and centre of face CDEF of the cube as shown in figure. The electric flux passing through the cube is :

Two shorts dipoles $(A,B)$, A having charges $\pm 2\mu \mathrm{C}$ and length 1 cm and $B$ having charges $\pm 4\mu \mathrm{C}$ and length 1 cm are placed with their centres 80 cm apart as shown in the figure. The electric field at a point $P$, equi-distant from the …