A rubber balloon has a lot of extra electrons deposited on it, giving it a negative charge. When the balloon is brought near an uncharged metal sphere as shown in figure:
The balloon will cause a polarization ofcharge in the sphere.
Negative charge creates electric field, andthat’s why balloon will cause polarization of charge in sphere. Balloon and sphere will interact, Coulomb's law states that:
The magnitude of the electrostatic force ofinteraction between two point charges is directly proportional to the scalar multiplication of the magnitudes of charges and inversely proportional to the square of the distance between them. The force is along the straight line joining them. If the two charges have the same sign, the electrostatic force between them is repulsive; if they have different sign, the force between them is attractive.