How You Detect Light

How You Detect Light

Vision begins when light rays are reflected off an object and enter the eyes through the cornea, the transparent outer covering of the eye. The cornea bends or refracts the rays that pass through a round hole called the pupil. The iris, or colored portion of the eye that surrounds the pupil, opens and closes (making the pupil bigger or smaller) to regulate the amount of light passing through. The light rays then pass through the lens, which actually changes shape so it can further bend the rays and focus them on the retina at the back of the eye. The retina is a thin layer of tissue at the back of the eye that contains millions of tiny light-sensing nerve cells called rods and cones, which are named for their distinct shapes. Cones are concentrated in the center of the retina, in an area called the macula. In bright light conditions, cones provide clear, sharp central vision and detect colors and fine details. Rods are located outside the macula and extend all the way to the outer edge of the retina. They provide peripheral or side vision. Rods also allow the eyes to detect motion and help us see in dim light and at night. These cells in the retina convert the light into electrical impulses. The optic nerve sends these impulses to the brain where an image is produced.The cornea is a transparent structure found in the very front of the eye that helps to focus incoming light. Situated behind the pupil is a colorless, transparent structure called the crystalline lens. A clear fluid called the aqueous humor fills the space between the cornea and the iris.Rods work at very low levels of light. We use these for night vision because only a few bits of light (photons) can activate a rod. Rods don't help with color vision, which is why at night, we see everything in a gray scale. The human eye has over 100 million rod cells.

Cones require a lot more light and they are used to see color. We have three types of cones: blue, green, and red. The human eye only has about 6 million cones. Many of these are packed into the fovea, a small pit in the back of the eye that helps with the sharpness or detail of images.

Other animals have different numbers of each cell type. Animals that have to see in the dark have many more rods than humans have.Another benefit to this layout is that the RPE can absorb scattered light. This means that your vision is a lot clearer. Light can also have damaging effects, so this set up also helps protect your rods and cones from unnecessary damage.

While there are many other reasons having the discs close to the RPE is helpful, we will only mention one more. Think about someone who is running a marathon. In order to keep muscles in the body working, the runner needs to eat special nutrients or molecules during the race. Rods and cones are similar, but instead of running, they are constantly sending signals. This requires the movement of lots of molecules, which they need to replenish to keep working. Because the RPE is right next to the discs, they can easily help reload photoreceptor cells and discs with the molecules they need to keep sending signals.   

Now that we know how these photoreceptor cells work, how do we use them to see different colors?

We have three types of cones. If you look at the graph below, you can see each cone is able to detect a range of colors. Even though each cone is most sensitive to a specific color of light (where the line peaks), they also can detect other colors (shown by the stretch of each curve).

Since the three types of cones are commonly labeled by the color at which they are most sensitive (blue, green and red) you might think other colors are not possible. But it is the overlap of the cones and how the brain integrates the signals sent from them that allows us to see millions of colors. For example, the color yellow results from green and red cones being stimulated while the blue cones have no stimulation.

The Fifth And Sixth Commandment

The Fifth Commandment: "You Shall Not Kill"
By the fifth commandment we are commanded to take proper care of our own spiritual and bodily well-being and that of our neighbor. The fifth commandment forbids murder and suicide, and also fighting, anger, hatred, revenge, drunkenness, reckless driving, and bad example.

The Sixth Commandent: " Thou shalt not commit adultery"
By the sixth commandment we are commanded to be pure and modest in our behavior. The sixth commandment forbids all impurity and immodesty in words, looks, and actions, whether alone or with others. The chief means of preserving the virtue of chastity are to avoid carefully all unnecessary dangers, to seek God's help through prayer, frequent confession, Holy Communion, and assistance at Holy Mass, and to have a special devotion to the Blessed Virgin.

 

Mirrors and lenses

Mirrors And Reflection Light

When you look at reflection in a metal spoon the spoon is like an mirror but not like an mirror in an bathroom. if you look in one side of the spoon your face would be upside down. Because the shape of a mirror affects the way light reflects from it an you can see your self in the bathroom mirrors differs from the image that you see in a spoon. an that mirror are classified by their shape. Their are three shapes of the mirror called plane , concave and convex.


Plane Mirrors

A plane mirror is a mirror with a flat planar reflective surface. For light rays striking a plane mirror, the angle of reflection equals the angle of incidence. The angle of incidence is the angle between the incident ray and the surface normal an imaginary line perpendicular to the surface.

 

Concave Mirror

A concave mirror, or converging mirror, has a reflecting surface that bulges inward away from the incident light. Concave mirrors reflect light inward to one focal point.They are used to focus light.

Strange Gods Around Us

In our society there are many slogans that had claimed happiness is found in the consumption of a certain product or in an possession of certain things. such as advertisements promise happiness in things and that it can turn into " Strange Gods" if we are not careful at this age.

Materialism- a tendency to consider material possessions and physical comfort as more important than spiritual values.

Vanity- excessive pride in or admiration of one's own appearance or achievements.

Profanity of music- Bad words in music

Obession In Sports- That people get obessed with sports and they put it in the center of their life and that its always winning in their life.

Which "Strange Gods" Do we think as teens struggle with most?

theirs no secret that our age in particular has turned defiance into a virtue and made obedience something to be mocked. This warped and rebellious worldview comes through in every aspect of popular culture. Entertainment, music, and even newscasts glorify revolt and rebellion against every form of authority. Statistics show that the average child living at home in America watches at least twenty-eight hours of television each week. For some kids, the total is much higher. Programming that targets young people is often the very worst at deliberately glamorizing sin. By the time most teenagers graduate from high school, they’ve been overexposed to the grossest kinds of evil through “entertainment” media in mind-numbing ways—so that nothing seems particularly appalling anymore.

Types Of Lnses

Lenses And Refraction Of Light

"How a Lens Refracts Light"
First lets consider a double convex lens. Suppose that several rays of light approach the lens; and suppose that these rays of light are traveling parallel to the principal axis. Upon reaching the front face of the lens, each ray of light will refract towards the normal to the surface. At this boundary, the light ray is passing from air into a more dense medium (usually plastic or glass). Since the light ray is passing from a medium in which it travels fast (less optically dense) into a medium in which it travels relatively slow (more optically dense), it will bend towards the normal line. This is the FST principle of refraction. This is shown for two incident rays on the diagram below. Once the light ray refracts across the boundary and enters the lens, it travels in a straight line until it reaches the back face of the lens. At this boundary, each ray of light will refract away from the normal to the surface. Since the light ray is passing from a medium in which it travels slow and more optically dense) to a medium in which it travels fast less optically dense, it will bend away from the normal line; this is the SFA principle of refraction.

Convex Lenses

Convex lenses are thicker at the middle. Rays of light that pass through the lens are brought closer together they converge. A convex lens is a converging lens. When parallel rays of light pass through a convex lens the refracted rays converge at one point called the principal focus.
 

Concave Lenses

Concave lenses are thinner at the middle. Rays of light that pass through the lens are spread out they diverge. A convex lens is a diverging lens. When parallel rays of light pass through a concave lens the refracted rays diverge so that they appear to come from one point called the principal focus.

  

The Third And Fourth Commandment

Third Commandment

" Remember To Keep The Lord's Day"
Meaning:
Remember the sabbath day to keep it holy. Six days you shall labor and do all your work; but the seventh day is a sabbath to the Lord your God in it you shall not do any work. 90. The sabbath was made for man, not man for the sabbath; so the Son of Man is lord even of the sabbath.

Fourth Commandment

"Honor Your Father And Mother"
Meaning:
 Honoring your father and mother is being respectful in word and action and having an inward attitude of esteem for their position. The Greek word for honor means “to revere, prize, and value.” Honor is giving respect not only for merit but also for rank. For example, some Americans may disagree with the President’s decisions, but they should still respect his position as leader of their country. Similarly, children of all ages should honor their parents, regardless of whether or not their parents “deserve” honor.