The range of angles over which a fiber optic strand can accept or emit light is expressed as its _____.

The range of angles over which a fiber optic strand can accept or emit light is expressed as its numerical aperture. This concept is crucial in fiber optics as it defines how much light a fiber can capture and subsequently transmit along its length. The numerical aperture (NA) is a dimensionless number that indicates the light-gathering ability of the fiber. It is mathematically defined as the sine of the acceptance angle of the light entering the fiber. A higher numerical aperture means the fiber can accept light from a wider range of angles, which enhances its ability to efficiently transmit optical signals.

Understanding the numerical aperture is essential for determining the performance of fiber optic cables in different applications. For example, fibers with a higher NA are typically better suited for applications involving divergent light sources, while those with a lower NA are better for applications requiring more directional light. This characteristic directly influences the overall behavior of the fiber regarding signal strength and transmission distances in optical communication systems.