Question 751: Electrostats & Capacitance

Question

Two identical conducting spheres with negligible volume have 2.1 nC and $$-$$0.1 nC charges, respectively. They are brought into contact and then separated by a distance of 0.5 m. The electrostatic force acting between the spheres is __________ $$	imes$$ 10$$-$$9 N.[Given : $$4\pi {\varepsilon _0} = {1 \over {9 	imes {{10}^9}}}$$ SI unit]

Accepted Answer

When they brought into contact & then separated by a distance = 0.5 m
Then charge distribution will be
The electrostatic force acting b/w the sphere is
$${F_e} = {{k{q_1}{q_2}} \over {{r^2}}}$$
$$ = {{9 	imes {{10}^9} 	imes 1 	imes {{10}^{ - 9}} 	imes 1 	imes {{10}^{ - 9}}} \over {{{(0.5)}^2}}}$$
$$ = {{900} \over {25}} 	imes {10^{ - 9}}$$
$$ \Rightarrow $$ $${F_e} = 36 	imes {10^{ - 9}}N$$

Electrostats & Capacitance

Choose the correct answer: