The shadow always seems to be black, regardless of the coloration of the substance or entity that casts it. It's darker than that of the rest of the area.
It depends upon whether the flashlight (source) comprises planar parallel beams but rather spherical.
The thickness of a shadow is generally determined by the separation or range between the item as well as the light source.
Therefore, a shadow would be a zone that is destitute of light compared to an optical element obstructing the passage of light.