Four charges $+Q$, $-Q$, $+Q$ and $-Q$ are situated at the corners of a square; in a sequence then at the centre of the square:

If the electric field at a distance $x$ from the origin is given as $E=\frac{100}{x^2}$, then the potential difference between the points situated at $x=10 \mathrm{m}$ and $x=20 \mathrm{m}$ is,

A circle of radius $R$ is drawn in a uniform electric field $E$ as shown in the fig. $V_A,V_B,V_c$ are respectively the potentials of points $A,B,C$ and $D$ on the circle then:

The electric field $\overrightarrow{E}$ is constant in both magnitude and direction. Consider a path of length d at an angle $\theta =60°$ with respect to field lines as shown in figure. The potential difference between points $1$ and $2$ is:-