The value of electric permittivity of free space is
$9 \times {10^9}\,N{C^2}/{m^2}$
$8.85 \times {10^{ - 12}}\,N{m^2}/{C^2}sec$
$8.85 \times {10^{ - 12}}\,{C^2}/N{m^2}$
$9 \times {10^9}\,{C^2}/N{m^2}$
The magnitude of electric force on $2\, \mu \,C$ charge placed at the centre $O$ of two equilateral triangles each of side $10 \,cm$, as shown in figure is $P$. If charge $A, B, C, D, E$ and $F$ are $2\, \mu \,C, 2\, \mu \,C, 2\, \mu \,C,-2\, \mu \,C, -2\, \mu \,C, -2\, \mu \,C$ respectively, then $P$ is :.....$N$
The plates $S$ and $T$ of an uncharged parallel plate capacitor are connected across a battery. The battery is then disconnected and the charged plates are now connected in a system as shown in the figure. The system shown is in equilibrium. All the strings are insulating and massless. The magnitude of charge on one of the capacitor plates is: [Area of plates = $A$]
Two spherical conductors $B$ and $C$ having equal radii and carrying equal charges in them repel each other with a force $F$ when kept apart at some distance. A third spherical conductor having same radius as that of $B$ but uncharged is brought in contact with $B$, then brought in contact with $C$ and finally removed away from both. The new force of repulsion between $B$ and $C$ is
Two positive point charges of unequal magnitude are placed at a certain distance apart. A small positive test charge is placed at null point, then
Assertion : Consider two identical charges placed distance $2d$ apart, along $x-$ axis. The equilibrium of a positive test charge placed at the point $O$ midway between them is stable for displacements along the $x-$ axis.
Reason: Force on test charge is zero