This is not a riddle. Its a prob. Ppl that have studied light or the human eye are mostly needed. Plz read on!

Question

Before i start, when i say my bathroom, its in my room, so when i refer to the light from the window, its a big window...
(I thought this one up myself)
3 or the 4 lightbulbs in my bathroom are broken. So when i go there in the day (with the door closed), its is very dim inside.
So you'd think that if i went to the bathroom at night (with the door opened) with 3 of the 4 lightbulbs broken, i wouldn't be able to see anything at all!
But wouldn't the bathroom look "brighter" because of the contrast between the one light bulb and the darkness outside? Therefore, i would be able to see better where i'm going in the bathroom at night then in the daylight?
I hope you understood my question.
I would like a more scientific answer, concerning the light, or the way our human eyes see the light.
Thank-you ;)

Answer 1

the retina is the sensory layer of the eye, and it contains two types of sensory cells: rods and cones. rods are great for seeing in dim light and detecting motion and shapes. cones require brighter light and enable us to see colors and detail. you can see a good diagram here: http://www.usm.maine.edu/psy/broida/101/retina.JPG

the retina is not a uniform mixture of rods and cones. cones are concentrated at the fovea, which is a thinner layer of cells (in fact it is entirely cones, no messenger cells or anything else). the light reflecting off objects in the center of your visual field is received at the fovea. the rest of the retina contains mostly rods, with a few cones mixed in. since the rods are more at the sides of your retina, and they are better at detecting light (even very dim points of light) and motion... when you are in the dark you tend to have really good peripheral vision. look at the night sky on a clear evening. concentrate on seeing the stars directly in front of you. do any of them look not particularly bright? now turn your head and try to see those dim stars through your peripheral vision. they look much brighter, don't they?

it takes a few moments for the eye to switch between primarily cone-vision and primarily rod-vision. you can test this by going from a well-lit area to a dark area, such as enterring a movie theater from outside (daytime). when you are outside, your eyes are adjusted for cone vision and you see lots of colors. when you go into the theater, you can't see anything for a minute or so, then your eyes slowly adjust and the rods take over. it gradually gets better... you can see shapes and recognize friends across the room, but everything is in shades of bluish gray. if you then leave suddenly and enter a bright room or go outside, your eyes switch back to cone vision after a bit.

there is another thing i haven't mentioned: the pupils. these are holes in the eye surrounded by smooth muscle. the muscles control the size of the opening. cameras work in a similar fashion... if too much light is coming in, things get "overexposed", it is hard to make out any detail. you are effectively blind, until your eyes adjust. it can be painful, too, if the amounts of light are significantly different. you will probably notice this if you decide to fix your bulbs and continue to make nighttime trips to the bathroom. when there is not much light, the pupil opening widens. the maximum opening of the pupil is about ten times the size of the minimum opening.

entering your dim bathroom from full sun is like going into the dark theater. if you stay there long enough, your rods will kick in and you'll see just fine. entering your dim (but lit) bathroom from complete darkness is like leaving the dark theater. your cones take over. in either case, you don't see "better" than usual, your eyes just adjust so that you are at your normal ability.

Answer 2

Your question is a bit confusing.

Our eyes have the ability to control how much light comes into them by dilating the pupils to let in more light or constricting them to keep out more light.

When you are in your light room in the day, your pupils are fairly constricted (made small), so not too much light comes in. Then you walk into your bathroom and shut the door, and it becomes very dim. Your eyes are not letting much light in, and there is not much light there.

If you stayed in there for several minutes, you would discover that you could see better after a bit. That is because your pupils would dilate (open up) and let in more light. Then when you went outside, the bright light outside would be a bit too bright.

At night, when you are in your room, your pupils are wide open to let in as much light as possible so you can see some in the dark. Then when you go in the bathroom and turn on the light, all of that light can come into your eye through the dilated pupils. So the room actually seems much brighter.

If you stayed in there for awhile, your eyes would constict a small bit more, so that when you went out again, your room would seem darker.

The actual amount of light does not change, but how much your pupils let in does. Just like if you opened your shade all the way or just a crack, different amounts of light would come in, although the actual sun shine outside would not have changed.

Answer 3

At night, you should be able to see better in the bathroom, but it's not because of contrast, but instead because your eyes have "adjusted" to the dark.

You have two kinds of light receptors in your eyes: cones, which work best in daylight, and rods, which are much more sensitive to light and help with night vision. During the day, you've been in bright light, and you're seeing with cones. When you walk into the bathroom, it is much dimmer, so you can't see well. If you wait 5 minutes or so, your rods will kick in, your eyes will "adjust" and it should seem brighter.

At night, you've been in the dark, so your eyes have already adjusted. That single bulb looks a whole lot brighter to the rod receptors at night than to the cone receptors you'd be using during the day. Hope this helps!

Answer 4

I think I get it...your bathroom should be brighter at night because there is more light coming from there than outside. Even if it does seem dim to you at first, your eyes adjust to the light. If there isn't as much light, your pupils dilate, or grow bigger, allowing more light in, and making it easier to see. The same thing happens when you turn your light off to go to sleep. It seems pitch black to you at first, but the little light that's coming through your window will enter throught your dilated pupils after some time and you'll be able to see.

Answer 5

I am part Italian and some Italians have light colored eyes. This is due to genetics. Blue eyes carry a recessive gene. You need to recessive genes for blue eyes. A family can have a couple of generations without blue eyes but if two people with recessive genes get together, the baby has about 25% chance of having blue eyes. EDIT: Honestly the reason for blue eyes is genetic. There is nothing magic about it and it has little to do with race. An African American with the recessive gene for blues eyes has the same chance as a Caucasian with the recessive gene in having a blue eyed child. What that shows is that someone, somewhere in the family line had blue eyes or was with someone who did and the gene was passed down. The people who keep giving the thumbs down on answers that state that it is genetic have very little knowledge of genetics and heredity. Also, Africa is a continent not a country and it has a wide variety of genetic differentiation. Just like North Europeans do not have some of the same characteristics as the Southern Europeans. People who live near sea ports tend to have varying characteristics for obvious reasons.

Answer 6

Your ability to see in your bathroom will pretty much be the same in either case. It's just that your mind is tricked by the comparison between the two situations of day and night. It seems darker during the day because the comparison is to a bright, daylit room. However, the eye more quickly adjusts from dark to bright than vice versa, so your eyes adjust to the light conditions more quickly when going from dark to light than from light to dark, but the difference between the two times is very small.

Answer 7

Well, you know when you've just come out a movie theater into the bright hallway, and you have to squint? It is because your eyes have to adjust. In the movie theater, your pupils were dialiated, or bigger, because it was dark. Your pupils wanted to take in as much light as they could, so they grew bigger. When you exited the theater, your eyes were exposed to large amounts of light because your eyes were dialated at the time, and had not adjusted. That is why you squinted, because your eyes were getting too much light. So, your pupils shrank and became smaller, taking in less light.

So, regarding your question, since it was daylight at the time, perhaps your eyes were adjusted and your pupils were smaller, so they didn't take as much light in as they could from that one working light bulb. That is why the room appeared dim. However, during the night, the pupils in your eyes were larger to take in as much light as they could. So, the light from the working light bulb appeared brighter at night because your pupils were larger, allowing them to see more light.

Hopefully this makes a bit of sense.. :)