A positively charged particle is placed near a negatively charged particle. What is the direction of the electric force between the two particles?

1. Analyze the question

The question asks for the direction of the electric force exerted between two particles with opposite charges (one positive and one negative).

2. Explain the concept

In electrostatics, the fundamental principle governing the interaction between charges is:

• Like charges repel: Two positive charges or two negative charges push each other away.
• Unlike charges attract: A positive charge and a negative charge pull each other toward one another.

The electric force is a vector quantity, meaning it has both magnitude and direction. By convention, the electric field lines originate from a positive charge and terminate at a negative charge. Similarly, the force of attraction between two opposite charges acts along the line joining them, pulling the positive charge toward the negative one and the negative charge toward the positive one.

3. Show the solution

• Step 1: Identify the nature of the interaction. Since one particle is positive and the other is negative, they will experience an attractive force.
• Step 2: Determine the direction of the force. The force on the positive particle is directed toward the negative particle, and the force on the negative particle is directed toward the positive particle.
• Step 3: Evaluate the options. Option D describes the force as being directed from the positive particle to the negative particle. This aligns with the standard convention of electric field direction and the vector of attraction between the two points.

4. Identify the answer

The correct option is D.

Note: While the force is mutual (both particles pull on each other), in the context of physics problems regarding the direction of the electric field or the force vector between two opposite charges, we describe the direction as moving from the source (positive) to the sink (negative).

5. Exam Tip

Memory Trick: Think of the positive charge as the "giver" and the negative charge as the "receiver." Electric field lines and the resulting attractive force vectors always point from the "giver" (positive) to the "receiver" (negative).