as radius of fiber increases the number of modes __________Select one:a. remains sameb. decreasec. increased. not dependent

To determine how the number of modes in a fiber optic system changes as the radius of the fiber increases, we need to consider the relationship between the fiber's radius and its modal properties.

Explanation

1. Understanding Fiber Modes: In fiber optics, a mode is a distinct, allowed pattern of light propagation within the fiber. The number of modes in a fiber is generally influenced by the fiber’s design, particularly its core diameter (radius) and the refractive index profile.

2. Relationship with Fiber Radius: As the radius of the fiber increases, the capacity for more light paths (modes) through the fiber also increases. This is because a larger diameter allows for more angles at which light can enter and propagate through the fiber, leading to additional modes.

3. Numerical Aperture (NA): The larger the diameter of the fiber, the higher the numerical aperture, which enhances the fiber’s ability to accept more light and, consequently, more modes can coexist.

Conclusion

Given the above analysis, the correct answer to the question is:

c. increased

Final Answer

As the radius of the fiber increases, the number of modes increases (option c).