Which of the following figure represents the electric field lines due to a single positive charge?

Point charges $+q$ and $-q$ are located at the vertices of a square with diagonals $2l$ as shown in the figure. The magnitude of the electric field strength at a point, located symmetrically with respect to the vertices of the square at a distance $x$ from its center is

The electric field lines on the left have twice the separation on those on the right as shown in figure. If the magnitude of the field at $A$ is $40 {\mathrm{Vm}}^{-1}$, what is  the force on $20 \mu \mathrm{C}$ charge kept at

Charges ${\mathrm{Q}}_1$ and ${\mathrm{Q}}_2$ are at points $\mathrm{A}$ and $\mathrm{B}$ of a right-angled triangle $OAB$. The resultant electric field at point $\mathrm{O}$ is perpendicular to the hypotenuse, then ${\mathrm{Q}}_1/{\mathrm{Q}}_2$ is proportional to:

A cube of side $a$ has point charges $+\mathrm{Q}$ located at each of its vertices except at the origin where the charge is $-\mathrm{Q}.$ The electric field at the centre of cube is:

Figure shows three arrangements of electric field lines. In each arrangement, a proton is released from rest at point A and then accelerated through point B by the electric field. Points A and B have equal separations in the three arrangements. If $p_1,p_2$ and $p_3$ are linear momentum of the proton at point B in the three arrangement respectively, then

A point charge $q$ is placed at the corner of a cube of side $a$ as shown in the figure. What is the electric flux through the face $ABCD$ ?

A charge $q$ is placed at one corner of a cube as shown in figure. The flux of electrostatic field $\overrightarrow{E}$ through the shaded area is: