• # question_answer A charged ball hangs from a silk thread of length l.  It makes an angle $\theta$ with a large charged conducting sheet P as shown in the figure. The surface charge density $\sigma$ of the sheet is proportional to: A)  $\cos \theta$                          B)  $\cot \theta$ C)  $\sin \theta$                          D)  $\tan \theta$

From the diagram,             $T\sin \theta =\frac{q\sigma }{2{{\varepsilon }_{0}}}$ and  $T\cos \theta =mg$ $\Rightarrow$               $\tan \theta \times \sigma$