When light passes from a low-density object to a high-density object, its speed will decrease.

Here's why:

* Index of Refraction: The speed of light in a medium is determined by its index of refraction (n). A higher index of refraction means light travels slower.

* Density and Refractive Index: Generally, denser materials have a higher refractive index. This is because the light waves interact more frequently with the tightly packed particles within a denser medium.

* Example: Light travels faster in air (low density) than in water (higher density).

Important Note: While the speed of light decreases, its frequency remains constant. The change in speed is compensated by a change in wavelength.