Refraction and Its Uses

Refraction and Its Uses

Done by: Guan Ruofei 3P3 06

Content

What is refraction of light? Spectacles Magnifying glass Camera Telescope Microscope References

What is refraction of light? Refraction of light is the change in direction of

a light ray due to a change in its speed. This is most commonly observed when a light ray passes from one medium to another (with different optical density) at an angle.

Spectacles

Spectacles are used to correct refractive errors of the eye by modifying the effective focal length of the lens in order to alleviate the effects of conditions such as nearsightedness (myopia), farsightedness (hyperopia) or astigmatism.

How do spectacles work? Some people have bad eyesight as their eyes’

lenses cannot refract light to the back their eyes. With spectacles, it helps to refract the light at an

correct angle so that light rays can meet at the back of the eye. This gives a sharp and clear image

Magnifying glass

A magnifying glass is a convex lens which is used to produce a magnified image of an object.

How does magnifying glass work?

The way a magnifying glass works is by bending light. As light passes through a convex lens, it is bent by the glass. Our eyes perceive the bent light as a bigger object, even though the object itself has not changed in size at all.

The magnifying glass must be placed closer to the object than the distance of the focal length of the glass so that the image is magnified.

Diagram showing how magnifying glass works.

The magnified image

EyeObject

Magnifying glass

Camera

A camera is a device that records images, either as a still photograph or as moving images known as videos or movies.

It consists of lens, recording surface, and etc.

How does a camera work? Cameras may work with the light of the visible spectrum

or with other portions of the electromagnetic spectrum.

A camera generally consists of an enclosed hollow with an opening at one end for light to enter, and a recording or viewing surface for capturing the light at the other end.

A majority of cameras have a lens positioned in front of the camera's opening to gather the incoming light and focus all or part of the image on the recording surface. The light can be focused as light bents when they enters the lens. This is due to the reflection of light.

Diagram showing how a camera works.

Telescope

A telescope is an instrument designed for the observation of remote objects by the collection of electromagnetic radiation. The first known practically functioning telescopes were invented in the Netherlands at the beginning of the 17th century.

How does a telescope work?

As the light rays travel through the lenses of the telescope, they are refracted.

In a telescope, the idea is to bend parallel light from very faraway objects into a small focus at the eye so that a sharp and clear image can be formed at the back of the eye.

Diagram showing how a telescope works

Microscope

A microscope is an instrument to see objects too small for the naked eye.

With the microscope, people can see bacteria, blood cells and other tiny organism or cells.

How does a microscope work?

A microscope uses the same trick as a refracting telescope — light waves being bent as they travel through glass. In a microscope, the idea is to bend diverging (spreading-out) light into a parallel path, then bend that parallel-path light into a small focus at the eye.

Diagram showing how a microscope works

Light enters the bottom, travels through the objective lenses and then through the eyepiece lenses.

References http://en.wikipedia.org/wiki/Refraction http://image.tutorvista.com/content/refraction-light/refracti

on-of-light-two-medium.jpeg http://morningnoonandnight.files.wordpress.com/2007/09

/spectacles.jpg http://en.wikipedia.org/wiki/Glasses http://en.wikipedia.org/wiki/File:Myopia.svg http://margotmystic.files.wordpress.com/2008/09/magnify

ing-glass.jpg http://www.ehow.com/how-does_4568247_magnifying-le

ns-work.html http://image.tutorvista.com/content/refraction-light/magnif

ied-image-formation-convex-lens.jpeg

References http://1.bp.blogspot.com/_sdNxRP_Hp3k/SmCQQGRi8II/

AAAAAAAAANQ/3QB_b3zGoTw/s400/canon-digital-ixus-960-is-camera.jpg

http://en.wikipedia.org/wiki/Camera http://www.phys.ufl.edu/~avery/course/3400/camera/cam

era_image_landscape.jpg http://otherbrooksbrother.files.wordpress.com/2008/02/

microscope.jpg http://www.yesmag.ca/how_work/microscope.html http://en.wikipedia.org/wiki/Microscope http://en.wikipedia.org/wiki/Telescope http://learn.uci.edu/media/OC08/11004/

OC0811004_RefractingTelesc.jpg http://scrapetv.com/News/News%20Pages/Science/

images-2/hubble-space-telescope.jpg