Question

The force between two conducting spheres of same radius having charges +8 μC and -4 μC separated by some distance in air is F. If the spheres are connected by a conducting wire and after some time the wire is removed, then the magnitude of the force between the two conducting spheres is

• A. $F$
• B. $\frac{F}{2}$
• C. $8F$
• D. $\frac{F}{4}$

Hint:

Remember that when charges are redistributed, the new force depends on the square of the charges involved.

Answer 1

The Correct Option is C

When the spheres are connected by a conducting wire, the charges redistribute equally. The new charge on each sphere becomes $\frac{+8 \, \mu C + (-4 \, \mu C)}{2} = 2 \, \mu C$. Using Coulomb's law for the force between two charges, the force is proportional to the square of the charge. Hence, the new force will be $8F$.