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 pith balls carrying equal charges are suspended from a common point by strings of equal length, the equilibrium separation between them is $r.$ Now the strings are rigidly clamped at half the height. The equilibrium separation between the balls now become
Positive point charges are placed at the vertices of a star shape as shown in the figure. Direction of the electrostatic force on a negative point charge at the centre $O$ of the star is
Two charges $ + 4e$ and $ + e$ are at a distance $x$ apart. At what distance, a charge $q$ must be placed from charge $ + e$ so that it is in equilibrium
A simple pendulum of period $T$ has a metal bob which is negatively charged. If it is allowed to oscillate above a positively charged metal plate, its period will
Suppose the charge of a proton and an electron differ slightly. One of them is $-e,$ the other is $(e + \Delta e).$ If the net of electrostatic force and gravitational force between two hydrogen atoms placed at a distanced (much greater than atomic size) apart is zero, then $\Delta e$ is of the order of $[$ Given: mass of hydrogen $m_h = 1.67 \times 10^{- 27}\,\, kg]$