Filters

Q&A - Ask Doubts and Get Answers
Q

Tell me? - Electrostatics - NEET

Two identical charged spheres suspended from a common point by two massless strings of lengths , are initially at a distance d (d << ) apart because of their mutual repulsion. The charges begin to leak from the both the spheres at a constant rate. As a result, the spheres approach each other with a velocity . Then varies as a function of the distance x between the spheres as:

• Option 1)

• Option 2)

• Option 3)

• Option 4)

130 Views

As discussed in

Coulombic force -

$\dpi{100} F\propto Q_{1}Q_{2}=F\propto \frac{Q_{1}Q_{2}}{r^{2}}=F=\frac{KQ_{1}Q_{2}}{r^{2}}$

- wherein

K - proportionality Constant

Q1 and Q2 are two Point charge

$T \cos \Theta=mg\:\:\:\:-(i)$

$T \sin \Theta=qt\:\:\:\:\:-(ii)$

$\tan \Theta=\frac{qt}{mg}=\frac{Kq^{2}}{x^{2}mg}$

$\frac{x}{2l}=\frac{Kq^{2}}{x^{2}mg}\:\:\:\:\Rightarrow q^{2}=\frac{x^{3}mg}{2lK}\:\:\:or \:\:\:q\propto x^{\frac{3}{2}}$

$\frac{dq}{dt}\propto \frac{3}{2}\sqrt x\:v$

Where $\frac{dq}{dt}=constant$

$\therefore V \propto\frac{1}{\sqrt x}=V\propto x ^{\frac{-1}{2}}$

Option 1)

This option is incorrect.

Option 2)

This option is incorrect.

Option 3)

This option is correct.

Option 4)

This option is incorrect.

Exams
Articles
Questions