Which property did Janssen most likely believe about light during the invention period?

• A. Light bends around objects.
• B. Light bounces off surfaces.
• C. Light travels in a curved path.
• D. Light is made up of waves.

Answer: (D)

Light’s nature during the invention period was being explored by instrument makers who were trying to understand how to control and image the world with optics. Thinking of light as waves offered a consistent way to explain observations that go beyond simple straight-line paths, such as why light of different colors behaves differently in materials and how patterns can form when light encounters edges or openings. Janssen, working with lenses and early optical devices, would be attuned to ideas about light that could account for these behaviors and help improve image formation, focusing, and color separation. While everyday behaviors like reflecting off surfaces or bending at interfaces are real, they’re explained by ray-like pictures rather than describing what light fundamentally is; describing light as waves captures the deeper property scholars were beginning to investigate at the time. So, the belief that light is made up of waves best fits the historical context and the kinds of phenomena that influenced early optical invention.