Find the electric field at point $P$ (as shown in figure) on the perpendicular bisector of a uniformly charged thin wire of length $L$ carrying a charge $Q.$ The distance of the point $P$ from the centre of the rod is $a=\frac{\sqrt{3}}{2} L$.
$\frac{\sqrt{3} Q }{4 \pi \varepsilon_{0} L ^{2}}$
$\frac{ Q }{3 \pi \varepsilon_{0} L ^{2}}$
$\frac{Q}{2 \sqrt{3} \pi \varepsilon_{0} L ^{2}}$
$\frac{ Q }{4 \pi \varepsilon_{0} L ^{2}}$
Figure shows a rod ${AB}$, which is bent in a $120^{\circ}$ circular arc of radius $R$. A charge $(-Q)$ is uniformly distributed over rod ${AB}$. What is the electric field $\overrightarrow{{E}}$ at the centre of curvature ${O}$ ?
An oil drop of $12$ excess electrons is held stationary under a constant electric field of $2.55 \times 10^{4}\; N\,C ^{-1}$ (Millikan's oil drop experiment). The density of the oil is $1.26 \;g \,cm ^{-3} .$ Estimate the radius of the drop. $\left(g=9.81\; m s ^{-2} ; e=1.60 \times 10^{-19}\; \,C \right)$
What is the magnitude of a point charge which produces an electric field of $2\, N/coulomb$ at a distance of $60\, cm$ $(1/4\pi {\varepsilon _0} = 9 \times {10^9}\,N - {m^2}/{C^2})$
Find ratio of electric field at point $A$ and $B.$ Infinitely long uniformly charged wire with linear charge density $\lambda$ is kept along $z-$ axis
The three charges $q / 2, q$ and $q / 2$ are placed at the corners $A , B$ and $C$ of a square of side ' $a$ ' as shown in figure. The magnitude of electric field $(E)$ at the comer $D$ of the square, is