The electric field in a region is given $\overrightarrow{ E }=\left(\frac{3}{5} E _{0} \hat{ i }+\frac{4}{5} E _{0} \hat{ j }\right) \frac{ N }{ C } .$ The ratio of flux of reported field through the rectangular surface of area $0.2\, m ^{2}$ (parallel to $y - z$ plane) to that of the surface of area $0.3\, m ^{2}$ (parallel to $x - z$ plane $)$ is $a : b ,$ where $a =$ .............
[Here $\hat{ i }, \hat{ j }$ and $\hat{ k }$ are unit vectors along $x , y$ and $z-$axes respectively]
$2$
$3$
$4$
$1$
Assertion : Electric lines of force never cross each other.
Reason : Electric field at a point superimpose to give one resultant electric field.
The figure shows two situations in which a Gaussian cube sits in an electric field. The arrows and values indicate the directions and magnitudes (in $N-m^2/C$) of the electric fields. What is the net charge (in the two situations) inside the cube?
A few electric field lines for a system of two charges $Q_1$ and $Q_2$ fixed at two different points on the $x$ -axis are shown in the figure. These lines suggest that:-
If a charge $q$ is placed at the centre of a closed hemispherical non-conducting surface, the total flux passing through the flat surface would be
If the number of electric lines of force emerging out of a closed surface is $1000$ , then the charge enclosed by the surface is .......... $C$