Three charges are placed at the vertices of an equilateral triangle of side ‘$a$’ as shown in the following figure. The force experienced by the charge placed at the vertex $A$ in a direction normal to $BC$ is
${Q^2}/(4\pi {\varepsilon _0}{a^2})$
$ - {Q^2}/(4\pi {\varepsilon _0}{a^2})$
Zero
${Q^2}/(2\pi {\varepsilon _0}{a^2})$
Two identical conducting spheres with negligible volume have $2.1\, nC$ and $-0.1\, nC$ charges, respectively. They are brought into contact and then separated by a distance of $0.5 \,m$. The electrostatic force acting between the spheres is $.......... \, \times 10^{-9} \,N$
[Given : $4 \pi \varepsilon_{0}=\frac{1}{9 \times 10^{9}} SI$ unit]
Force between two identical spheres charged with same charge is $F$. If $75\%$ charge of one sphere is transfered to the other sphere then the new force will be
Three points charges are placed at the corners of an equilateral triangle of side $L$ as shown in the figure.
A paisa coin is made up of $\mathrm{Al - Mg}$ alloy and weighs $0.75\, g$. It has a square shape and its diagonal measures $17$ $\mathrm{mm}$. It is electrically neutral and contains equal amounts of positive and negative charges.
A charge $q$ is placed at the centre of the line joining two equal charges $Q$. The system of the three charges will be in equilibrium, if $q$ is equal to