Final answer:
When a positively charged object is grounded, electrons flow from the ground to the object, neutralizing its positive charge. This happens because the grounding provides a path for the electrons to neutralize the excessive positive charge, inducing a negative charge on the object.
Step-by-step explanation:
When a positively charged object is grounded, electrons from the ground are attracted to and flow towards the object to neutralize its charge. This flow of electrons is due to the electric force exerted by the positive charge on the freely moving conduction electrons, pulling them toward the object. Grounding provides a pathway for the electrons to travel from the earth's ample supply to the object in question, balancing out the excessive positive charge.
For instance, let's consider a neutral metal sphere. If a positively charged rod is brought near the sphere, it will polarize the sphere, causing the electrons to move closer to the side nearest to the rod. Upon grounding the sphere, electrons from the earth will flow up into the sphere, attracted by the positive charge on the rod. When the ground connection is broken and then the rod is removed, the sphere is left with an induced negative charge due to the extra electrons, which have remained on the surface.