Question

A point charge q1 exerts a force F on another charge q2 one other charge q3 be placed quite near to charge q2 then the force that charge q1 exerts on q2 will be ?

• A. F
• B.

  F

• C. < F
• D. Zero

Answer 1

Answer: (A)

F

Answer 2

According to Coulomb's law, the force exerted by a point charge $q_1$ on another point charge $q_2$ at a distance $r$ is given by $F = k \frac{|q_1 q_2|}{r^2}$, where $k$ is Coulomb's constant. This force depends only on the magnitudes of the charges $q_1$ and $q_2$ and the distance $r$ between them.

The principle of superposition states that the total force on a given charge due to a collection of other charges is the vector sum of the individual forces exerted by each of the other charges on the given charge. Crucially, this principle implies that the force exerted by one charge on another is independent of the presence of other charges.

In this problem, we are asked about the force that charge $q_1$ exerts on charge $q_2$. Initially, this force is given as F. When a third charge $q_3$ is placed near $q_2$, the force exerted by $q_1$ on $q_2$ is not affected by the presence of $q_3$. The charge $q_3$ will exert its own force on $q_2$, and the net force on $q_2$ will be the vector sum of the force from $q_1$ and the force from $q_3$. However, the question specifically asks for the force that charge $q_1$ exerts on $q_2$.

According to the principle of superposition, the force exerted by $q_1$ on $q_2$ remains unchanged, regardless of the presence of $q_3$. Therefore, this force will still be F.