Optical fibres transmit light along its axis, by the process of

Options

A. total internal reflection
B. refraction
C. interference
D. diffraction

Explanation

To solve the question "Optical fibres transmit light along its axis, by the process of," we need to analyze the options provided and understand the principles behind optical fibers.

### Step-by-Step Solution:

1. **Understanding Optical Fibers**:
- Optical fibers are thin strands of glass or plastic that transmit light. They are designed to carry light signals over long distances with minimal loss.

2. **Identifying the Mechanism of Light Transmission**:
- The key to how optical fibers work lies in the way light behaves at the boundaries between different media.

3. **Exploring the Options**:
- **A. Total Internal Reflection**: This occurs when light travels from a denser medium to a less dense medium at an angle greater than the critical angle. At this angle, all the light is reflected back into the denser medium, allowing it to travel along the fiber.
- **B. Refraction**: This is the bending of light as it passes from one medium to another. While refraction does occur at the boundaries of the fiber, it is not the primary mechanism for light transmission in optical fibers.
- **C. Interference**: This is a phenomenon that occurs when two or more waves overlap and combine. It is not the mechanism used in optical fibers for light transmission.
- **D. Diffraction**: This refers to the bending of light waves around obstacles. Like interference, it is not the primary mechanism for light transmission in optical fibers.

4. **Conclusion**:
- The correct answer is **A. Total Internal Reflection**. This is the process that allows optical fibers to transmit light along their axis effectively.

### Final Answer:
Optical fibres transmit light along its axis by the process of **Total Internal Reflection**.

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