The phenomenon you are describing is called indirect reflection or multiple reflections. When light encounters a mirror, it follows the law of reflection, which states that the angle of incidence is equal to the angle of reflection. This law holds true for each individual reflection of light rays off the mirror surface.
In the case of an interior of a light fixture, the light rays originating from the interior might not have a direct pathway to the mirror. However, they can still reach the mirror through multiple reflections. The light rays bounce off several surfaces inside the fixture until they eventually reach the mirror.
Each time a light ray reflects off a surface, it changes direction according to the law of reflection. By bouncing off multiple surfaces, the light rays can take a circuitous path, undergoing numerous reflections, until they finally reach the mirror.
The mirror then reflects these rays according to the law of reflection once again. The reflected rays eventually reach our eyes, and we perceive them as an image of the interior of the light fixture.
It's important to note that the image formed through multiple reflections may not be as clear or sharp as a direct reflection, as each reflection can introduce some distortion or loss of intensity. However, multiple reflections allow light to travel indirectly and reach the mirror, enabling us to see the interior of the light fixture.