What is the function of a light source in fiber optic testing?

The function of a light source in fiber optic testing is primarily to shine light or a laser at the end of the fiber. This process is crucial for evaluating the fiber's performance and integrity. When light is injected into the fiber, it allows technicians to assess how well the fiber transmits this light, which is essential for testing the quality of the fiber optic link.

By shining light into the fiber, the technician can observe how much light exits the other end, which offers insights into the fiber's loss characteristics and potential faults. This method is widely used in various testing scenarios, such as continuity testing and loss measurements, making it a fundamental aspect of fiber optic diagnostics and maintenance.

The other options relate to different aspects of fiber optic testing or functions of other tools. For example, measuring signal strength and determining cable loss are secondary processes that often rely on the initial injection of light into the fiber, while connecting cables pertains to establishing physical connections rather than the testing process itself.