What is the approximate size of the smallest object visible with the unaided eye?

Question

What is the approximate size of the smallest object visible with the unaided eye?

Answer 1

We see objects because light either passes through them or is reflected off them and enters our eye, where it is translated into an image. However, we are limited in what we can see with the unaided eye. Without the aid of magnifying lenses, the smallest object we can resolve is approximately 100 um or 0.1 mm in diameter, which is approximately the size of a fine pencil dot.