A small uncharged conducting sphere is placed in contact with an identical sphere carrying a charge of 4×10⁻⁸ C and then removed to a distance such that the force of repulsion between them is 9×10⁻³ N. The distance between them is (Take1/(4πε₀)=9×10⁹SI units)

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(4) 2 cm. Identical spheres in contact share the charge equally, so each carries q=(4×10⁻⁸)/2=2×10⁻⁸ C. F=(kq²)/(r²)⇒ r²=(kq²)/F. kq²=9×10⁹×(2×10⁻⁸)²=9×10⁹×4×10⁻¹⁶=3.6×10⁻⁶. r²=(3.6×10⁻⁶)/(9×10⁻³)=4×10⁻⁴ m². r=2×10⁻² m =2 cm.

A small uncharged conducting sphere is placed in contact with an identical sphere carrying a charge of 4×10⁻⁸ C and then removed to a distance such that the force of repulsion between them is 9×10⁻³ N. The distance between them is (Take1/(4πε₀)=9×10⁹SI units)

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