New posts in Geometric Optics

Why do sunbeams diverge even though the sun is much more than a few kilometers away?

Is it possible to start fire using moonlight?

How to calculate the refracted light path when refraction index continuously increasing?

If I reflect light from a projector using a mirror, then is the reflected image real or virtual?

Reflection at intersection of two mirrors

How do a microscope's optics expose defects in the user's vision?

Is there any optical component that uniformizes the incoming light?

Fresnel distance and Geometrical limit

If light rays obey to the wave equation, why can they be thought as straight lines?

Why does a blue sky at dusk appear nearly black through a telescope?