You are here:

Physics/physics - light


At night it is difficult to see through a closed glass window from a well lighted room, but it is relatively easy when lights are switched off. why?

This has more to do with your eyes than anything else.  The brightness in the room is partially reflected off of the glass, and is quite high when compared to the outside.  Therefore your pupils contract and your retinas are generally overwhelmed by the stronger light signal inside the room and reflecting off of the glass.  The light from outside is still coming in, it's just that between your contracted pupils (meaning not as much gets through to your retina) and the overwhelming amount of light from inside, you can't perceive it.


All Answers

Answers by Expert:

Ask Experts


Dr. Stephen O. Nelson


I can answer most basic physics questions, physics questions about science fiction and everyday observations of physics, etc. I'm also usually good for science fair advice (I'm the regional science fair director). I do not answer homework problems. I will occasionally point out where a homework solution went wrong, though. I'm usually good at explaining odd observations that seem counterintuitive, energy science, nuclear physics, nuclear astrophysics, and alternative theories of physics are my specialties.


I was a physics professor at the University of Texas of the Permian Basin, research in nuclear technology and nuclear astrophysics. My travelling science show saw over 20,000 students of all ages. I taught physics, nuclear chemistry, radiation safety, vacuum technology, and answer tons of questions as I tour schools encouraging students to consider careers in science. I moved on to a non-academic job with more research just recently.

Ph. D. from Duke University in physics, research in nuclear astrophysics reactions, gamma-ray astronomy technology, and advanced nuclear reactors.

©2017 All rights reserved.