Write equation of electric field by system of $\mathrm{'n'}$ charges.

A total charge $q$ is divided as $q_1$ and $q_2$ which are kept at two of the vertices of an equilateral triangle of side a. The magnitude of the electric field $E$ at the third vertex of the triangle is to be depicted schematically as a function of $x=q_1 / q$. Choose the correct figure.

For the given figure the direction of electric field at $A$ will be

An electron experiences a force equal to its weight when placed in an electric field. The intensity of the field will be

The charge distribution along the semi-circular arc is non-uniform . Charge per unit length $\lambda $ is given as $\lambda  = {\lambda _0}\sin \theta $ , with $\theta $ measured as shown in figure. $\lambda_0$ is a positive constant. The radius of arc is $R$ . The electric field at the center $P$ of semi-circular arc is $E_1$ . The value of $\frac{{{\lambda _0}}}{{{ \in _0}{E_1}R}}$ is

A charge $Q$ is distributed over a line of length $L.$ Another point charge $q$ is placed at a distance $r$ from the centre of the line distribution. Then the force expericed by $q$ is