Final answer:
A candle would be the appropriate addition to create a sanctuary lamp, providing a soft glow that complements the red light and contributes to the peaceful atmosphere of a sanctuary.
Step-by-step explanation:
The question "What can be added to create a sanctuary lamp?" pertains to the category of lighting fixtures within the broader field of physics. Specifically, it relates to the study of light sources and their characteristics. To create a sanctuary lamp, one would typically use a candle, which provides soft, warm light that can add to the ambiance and reverence of a sanctuary setting. A candle would fit the description as it's the simplest form of lighting that fits with the theme of a sanctuary lamp, typically used for religious or meditative purposes. It also produces a soft glow similar to the red light mentioned in the question, enhancing the sensation of tranquility within the sanctuary.