Consider a uniform electric field $E =3 \times 10^{3} i\; N / C .$
$(a)$ What is the flux of this field through a square of $10 \;cm$ on a side whose plane is parallel to the $y z$ plane?
$(b)$ What is the flux through the same square if the normal to its plane makes a $60^{\circ}$ angle with the $x -$axis?
$(a)$ Electric field intensity, $E =3 \times 10^{3} \hat{ i } \,N / C$
Magnitude of electric field intensity, $| E |=3 \times 10^{3} \,N / C$
Side of the square, $s=10 \,cm =0.1\, m$
Area of the square, $A=s^{2}=0.01 \,m ^{2}$ The plane of the square is parallel to the $y-z$ plane. Hence, angle between the unit vector normal to the plane and electric field, $\theta=0^{\circ}$
Flux ( $\phi$ ) through the plane is given by the relation, $\phi=| E | A \cos \theta=3 \times 10^{3} \times 0.01 \times \cos 0^{\circ}=30 \,N\, m ^{2} / C$
$(b)$ Plane makes an angle of $60^{\circ}$ with the $x$ - axis. Hence, $\theta=60^{\circ}$ Flux, $\phi=| E | A \cos \theta$$=3 \times 10^{3} \times 0.01 \times \cos 60^{\circ}$
$=30 \times \frac{1}{2}=15\; N \,m ^{2} / C$
Figure shows electric field lines due to a charge configuration, from this we conclude that
A few electric field lines for a system of two charges $Q_1$ and $Q_2$ fixed at two different points on the $\mathrm{x}$-axis are shown in the figure. These lines suggest that $Image$
$(A)$ $\left|Q_1\right|>\left|Q_2\right|$
$(B)$ $\left|Q_1\right|<\left|Q_2\right|$
$(C)$ at a finite distance to the left of $\mathrm{Q}_1$ the electric field is zero
$(D)$ at a finite distance to the right of $\mathrm{Q}_2$ the electric field is zero
A hollow cylinder has a charge $q$ coulomb within it. If $\phi$ is the electric flux in units of $volt-meter$ associated with the curved surface $B,$ the flux linked with the plane surface $A$ in units of $V-m$ will be
When the electric flux associated with closed surface becomes positive, zero or negative ?
Draw electric field by negative charge.