Question

Two identical sphere having charge q and -3q exerts force on each other. Then the sphere are torched with each other and kept at the same separation. The magnitude of new force btw tge sphere will be

Answer 1

Explanation:

$F_{1}$ be the initial force between the 2 charges.

$F_{2}$ be the force between the two charges after the touching of spheres.

Initial Force

$F_{1} = \frac{ k q_{1}. -3q_{2} }{r^{2} }$ ( . is multiplication)

$F_{1} = -3 \frac{k q^{2} }{r^{2} }$

$\frac{F_{1} }{-3} = \frac{k q^{2} }{r^{2} }$

Charges after touching of spheres

New charge = $\frac{q - 3q}{2}$ = -q

New force

$F_{2} = \frac{k q^{2} }{r^{2} }$

$F_{2} = \frac{F_{1} }{-3}$

Magnitude of new force is 1/-3 times the initial force.