What component lines the back of the gauge glass to display liquid level?

The component that lines the back of the gauge glass to display liquid level is a prismatic lens strip. This strip serves a crucial function in enhancing the visibility of the liquid level by using refraction to project a clear and distinct image of the liquid’s height. When light passes through the prismatic lens, it bends and directs the light in such a way that it highlights the interface between the liquid and air, allowing for an accurate and easily readable indication of the liquid level within the gauge.

Other options, such as a reflective surface, may contribute to visibility but do not specifically enhance the clarity of the liquid level indication in the same way that a prismatic lens does. Optical fibers and LED backlights may be used in various display technologies, but they do not line the back of the gauge glass and are therefore not relevant. In this context, the prismatic lens strip is uniquely designed for this purpose, making it the correct choice.