Visualizing the formation of a VIRTUAL IMAGE by a lens

What's a "virtual image"? In the context of lenses, a virtual image is formed when rays appear to come from a specific location BEHIND a lens. In this video, I simulate this effect when a magnifying glass is used to magnify my eye in front of my webcam. A shoutout to    / @ivereadthesequel   Thanks for raising this question in my prior video on collimation, which was the one here:    • Why the most practical definition for coll...   EDIT: At around 6:50 min, I incorrectly mentioned that the ratio given by the virtual image height (264 mm) divided by the object height (35 mm) gives the 1.8 times magnification seen by the webcam. But of course, this is not the case. That ratio 264 mm/35 mm actually yields about 7.5x, which is the magnification of the virtual image relative to the object. The correct way to get the final magnification as seen by the webcam is given by: M = mo/[1 + (So/S)(mo - 1)], where M is the final magnification, mo is the 7.5x magnification (i.e., it is 264 mm divided by 35 mm), "So" is the distance between the object and the magnifying glass, and "S" is the distance between the object and the webcam. The values are: mo = 7.5, So = 169 mm, and S = 350 mm. Plugging these values into the above formula yields M ~ 1.81x, which is roughly the magnification seen by the webcam (the ~ symbol represents an approximation). This formula is derived easily using the algebra of first-order optics. I had completely forgotten about explaining this in the video! (It was around 4 am when I created the video, so you can see how sleep deprivation affects brain function!) LOL! FOLLOW-UP: See the following video for the derivation of the above formula and explanation of the reason why the magnification seen by the webcam is different from the magnification of the virtual image:    • What is the magnification produced when yo...