Suppose an electrically charged ruler transfers some of its charge by contact to a tiny plastic sphere. will the ruler and the sphere attract or repel afterwards? explain your reasoning

Here ball and rod will repel each other as they are of similar charges

Explanation:

As we know that the two charges attract or repel each other by electrostatic force

This force is given as

so we know if two charges are similar in nature then they will repel each other and if the two charges are opposite in nature then they will attract each other

So here when rod touch the ball then it transfer its charge to the ball and due to similar charges in ball and rod they both repel each other

electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia