Electric field at centre $O$ of semicircle of radius $a$ having linear charge density $\lambda$ given is given by
$\frac{\lambda }{{2\pi {\varepsilon _0}a}}$
$\frac{\lambda }{{2\pi {\varepsilon _0}{a^2}}}$
$\frac{\lambda }{{4{\pi ^2}{\varepsilon _0}a}}$
$\frac{{{\lambda ^2}}}{{2\pi {\varepsilon _0}a}}$
Give reason : ''Small and light pieces of paper are attracted by comb run through dry hair.''
The number of electrons to be put on a spherical conductor of radius $0.1\,m$ to produce an electric field of $0.036\, N/C$ just above its surface is
Explain electric field and also electric field by point charge.
Two point charges $q_{1}$ and $q_{2},$ of magnitude $+10^{-8} \;C$ and $-10^{-8}\; C ,$ respectively, are placed $0.1 \;m$ apart. Calculate the electric fields at points $A, B$ and $C$ shown in Figure
Charges $q$, $2q$, $3q$ and $4q$ are placed at the corners $A$,$ B$,$ C$ and $D$ of a square as shown in the following figure. The direction of electric field at the centre of the square is along