Two small spherical balls each carrying a charge $Q = 10\mu C\ (10\ micro - coulomb)$ are suspended by two insulating threads of equal lengths $1m$ each, from a point fixed in the ceiling. It is found that in equilibrium threads are separated by an angle $60^{o}$ between them, as shown in the figure. What is the tension in the threads (Given $:\frac{1}{\left( 4\pi\varepsilon_{0} ight)} = 9 imes 10^{9}Nm/C^{2})$ [image:1_image71.emf]

Question

Two small spherical balls each carrying a charge $Q = 10\mu C\ (10\ micro - coulomb)$ are suspended by two insulating threads of equal lengths $1m$ each, from a point fixed in the ceiling. It is found that in equilibrium threads are separated by an angle $60^{o}$ between them, as shown in the figure. What is the tension in the threads (Given $:\frac{1}{\left( 4\pi\varepsilon_{0} ight)} = 9 	imes 10^{9}Nm/C^{2})$ [image:1_image71.emf]

Dr. Abubacker · Accepted Answer

(b) In the following figure, in equilibrium $F_{e} = T\sin 30^{o},\ r = 1m$
[image:1_image276.emf]
$\Rightarrow 9 	imes 10^{9}.\frac{Q^{2}}{r^{2}} = T 	imes \frac{1}{2}$
$\Rightarrow 9 	imes 10^{9}.\frac{\left( 10 	imes 10^{- 6} ight)^{2}}{1^{2}} = T 	imes \frac{1}{2}\  \Rightarrow T = 1.8\ N$

Explanation

Reviewed by Dr. Abubacker

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