Given below are two statements labelled as Assertion (A) and Reason(R )
Assertion (A) : Two beams of electrons travelling in the same direction repel each other.
Reason (R ): The electrostatic interaction is less than the magnetic interaction.

Options

A. Both A and R are true and R is also the correct explanation of A.
B. Both A and R are true but R is not the correct explanation of A.
C. A is true but R is false.
D. A is false and R is also false.

Answer

To solve the question regarding the assertion and reason provided, we need to analyze both statements carefully.

### Step-by-Step Solution:

1. **Understanding the Assertion (A)**:
- The assertion states that "Two beams of electrons traveling in the same direction repel each other."
- Electrons are negatively charged particles. According to Coulomb's law, like charges repel each other. Therefore, since both beams consist of electrons (which are negatively charged), they will indeed repel each other.

2. **Understanding the Reason (R)**:
- The reason states that "The electrostatic interaction is less than the magnetic interaction."
- When charged particles (like electrons) are in motion, they create a magnetic field. The interaction between two moving charges can be described by both electrostatic and magnetic forces.
- However, in this case, we need to analyze the nature of the forces involved. The electrostatic force between the two beams of electrons (which is repulsive) is significant because both beams are composed of like charges.

3. **Comparing Electrostatic and Magnetic Forces**:
- The electrostatic force (Coulomb's force) acts between the charges regardless of their motion and is given by \( F_e = k \frac{|q_1 q_2|}{r^2} \), where \( k \) is Coulomb's constant, \( q_1 \) and \( q_2 \) are the charges, and \( r \) is the distance between them.
- The magnetic force, on the other hand, arises due to the motion of the charges and can be attractive or repulsive depending on the direction of the currents (or motion of charges).
- For two parallel currents (or moving charges in the same direction), the magnetic force is attractive. However, in this case, the repulsive electrostatic force is stronger than the attractive magnetic force.

4. **Conclusion**:
- The assertion is true: the two beams of electrons repel each other.
- The reason is false: the electrostatic interaction is not less than the magnetic interaction; in fact, it is greater in this scenario.
- Therefore, the correct conclusion is that the assertion is true, but the reason is false.

### Final Answer:
- Assertion (A) is true.
- Reason (R) is false.