my question is !......

Asked by  | 13th Jun, 2009, 03:38: PM

Expert Answer:

Electrostatic force of repulsion between the spheres  =  F  ( Say )

Now, F =( 1/4Πε0) ( product of charges of the two spheres / square of the distance between them )

Distance between the spheres = 2l sin θ

Charge on each sphere = q

so, F = ( 1/4Πε0) ( q / 2l sin θ )2

   Now in equilibrium ,

    F = mg tan θ

or, ( 1/4Πε0) ( q / 2l sin θ )2  = mg tan θ

or,  q2 / 4 l2 sin θ2  = ( 4Πε) mg tan θ

or,  q2  = 4 mg l2 sin θ2  tan θ ( 4Πε)

Hence proved.

Answered by  | 15th Jun, 2009, 12:52: PM

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