Final answer:
Making a map layer transparent reduces its visibility, allowing underlying layers to be seen through it. In terms of light transitioning from a vacuum into diamond, the wavelength decreases when entering the denser medium and then returns to normal upon exiting.
Step-by-step explanation:
When you make a layer in a map transparent, it reduces the layer's visibility. This means that the features of the underlying layers become more visible, and you can see through the transparent layer to these features beneath it. However, making a layer transparent does not increase its visibility, have no effect on visibility, or change the layer's color. The transparency feature is commonly used in Geographic Information Systems (GIS) to help users effectively analyze multiple layers of data at once.
Regarding the aspect of monochromatic green light when it passes from a vacuum into diamond, the wavelength decreases. When light enters a medium with a higher refractive index, such as diamond, from a less dense medium like a vacuum, the speed of light decreases, leading to a shorter wavelength. Upon exiting the diamond into a vacuum or a less dense medium, the light's speed increases again and thus the wavelength also increases, returning to its original value before entry.