Question

Like charges ….. and unlike charges …..
A) repel, attract
B) attract, repel
C) always attract
D) always repel

Answer 1

Hint: Like charges refer to positive-positive/negative-negative charges whereas unlike charges refer to positive-negative/negative-positive charges. The interaction between different charges when they are brought closer, can be explained with the help of transfer of virtual photons.

Complete answer:
Like charges refer to positive-positive/negative-negative charges whereas unlike charges refer to positive-negative/negative-positive charges. Repulsion refers to the force which makes two charges move away from each other while attraction refers to the force which makes two charges to come in contact with each other.
There are two types of charges which we see in nature. They are positive charges and negative charges. Most of us would have experienced the attractive force between a piece of paper and a scale, rubbed with our hands. At the same time, some of us would have experienced the repulsive force which causes damage to electronic components while working with them. These magical forces in nature are termed as electrostatic forces.
Electrostatic force can be explained with the help of quantum mechanics. A positive charge contains an excess number of photons (protons) in it whereas a negative charge contains a smaller number of photons in it. When a positive charge is brought closer to a negative charge, excess number photons from the positive charge get transferred to the negative charge, so that the number of photons in both the charges are balanced. This virtual transfer of photons from a positive charge to a negative charge causes an attractive force between them. Now, when a positive charge is brought closer to another positive charge, once the virtual transfer of photons occurs, there is an excess number of photons in both the charges, which tend to repel them away from each other. The same happens when two negative charges are brought closer. But here, it is the excess number of electrons, which causes repulsion among the two negative charges. Thus, using quantum mechanics, electrostatic attraction and repulsion are explained with the help of transfer of virtual photons.
Therefore, like charges repel and unlike charges attract.

Hence, the correct answer is option A.

Note:
Students can also relate electrostatic attraction and repulsion to Newton's third law of motion, which states that there is an equal and opposite reaction for every action. Attraction between two unlike charges can be explained by considering two unlike charges exerting a pulling force on each other whereas repulsion between two like charges can be explained by considering two like charges exerting a pushing force on each other.