Light and the Eye study guide

Science test on

Monday, November 24th

 

Students will need to identify the parts of the eye- this is a separate study guide.

Protective Eye Parts

 

Iris: - the colored part of our eye-protects the eye by either making the pupil appear smaller or bigger. When there is not enough light- the iris becomes smaller which makes the pupil look very large. This allows the pupil to let in more light. If there is too much light- the iris becomes larger which makes the pupil appear small. This keeps too much light from entering the eye.

 

Sclera- the white of our eye- when something is in our eye the sclera rushes blood to the veins in our eyes to help push things out of our eye.

 

Cornea- the clear covering that covers the pupil and iris- The covering keeps things out of the pupil hole.

 

Eyelash- the little hairs attached to the eye lids- help sweep away dust, dirt and snow so that they don’t get into our eyes.

 

Eyebrow- the hairs above our eyes- help keep sweat out of our eyes by guiding it to the outside of our face.

 

Eye lids- the skin that covers the eye when closed- the eye lids help to keep our eyes moist, closes automatically when something is coming quickly towards them, and works with the sclera to clear the eye.

 

Tear gland and tear duct- the gland “Mr. Peanut” is in the outer corner above each eye and it creates the tears that keep our eyes moist, helps show emotion and cleans out our eyes. Our tears are also the “sleep” caught in our eyes in the morning. The tear duct is the drain in the corner of each eye near the nose. The duct drains tears from our eyes and down into our noses.

 

 

Know these definitions:

- Spectrum: all the colors (ROYGBIV) that come together to make up white light

- Prism: a transparent object that is used to separate white light into the spectrum of colors.

- Refract: to bend

- Reflect: to bounce back

- Transparent: You can see clearly through it and light can pass through it. (A window, eye glass lens, glass, water.)

- Translucent: You can not see clearly through it, you can see shadows of objects. Light can pass through it. (Most colored glass or glass with a design, fluorescent light covers, some shades, gauzy curtains).

- Opaque: You can not see through it. No light can pass through it. (Person, car, tree, wall, desk, chair.)

- Convex: curved outward- Larger view, used in stores to see around corners. Used in microscopes.

- Concave: curved inward- smaller view, objects appear upside down. Used in telescopes.

 

Know this information:

- Light travels in a straight line.

- Light travels in waves.

- Light is energy.

-We can only see things when light hits an object and bounces off it. The light from the object then travels through our pupils which creates an upside-down image on our retina. The image then travels on the optic nerve to the brain, where it is turned right side up again.

- Dark objects absorb more light than light colored objects. This is why dark clothing is hotter in the summer. It is collecting more energy from the light.

-The best object to reflect something would be a flat mirror- plane mirror. It creates an exact reflection, only backwards.

-Light is bending and slowed down when it is refracted.

-A transparent object, such as water or a lens, is used to refract light.

-When light is blocked by an opaque object, a shadow of the object is formed.

-White light is made up of a spectrum of colors (all the colors of the rainbow).

- A prism or a drop of water can be used to break up white light into a spectrum.

- ROY G BIV- Red, orange, yellow, green, blue, indigo, and violet