Experiment: PINHOLE PROJECTOR

HOW DO OUR EYES WORK?

Experiment: PINHOLE PROJECTOR

You will need: - A shoe box - A piece of greaseproof paper - A torch Instructions: 1.- Push a drawing pin into the middle of one end of the shoe box. 2.- Cut out a rectangular window at the other end of the box and tape greaseproof paper over it. 3.- Cut another piece of greaseproof paper big enough to cover the lightbulb end of a torch. 4.- Draw a picture on the paper, colour and tape it on the torch. 6.- Stand 1 m from the torch looking through the viewer and pointing the pinhole at the light.

 

On the viewer we can see the picture of the tree upside down.

What's going on?

Light from the torch passes through the pinhole onto your viewer, and rays from the bottom hit the top. These rays cross over when they pass through the pinhole, so you see the picture upside down.

Our eyes work the same as the pinhole projector. The pinhole is like our pupil and the the viewer like our retina.

 

How do we see colours?
The surface of an object reflects some colors and absorbs all the others. We perceive only the reflected colors. An object appears white when it reflects all the colours and black when it absorbs all of them. We can see the apple red because the skin of the apple reflects red colour and absorbs the rest of them.

First of all, light enters our eye through the pupil. The light focusses onto the back part of the eye, called the retina. The retina is covered of two types of cells, called rods and cones. The rods look like tiny cylinders that detects light. Cones detect colour. There are three different types of cones. Each type will respond to a different colour, for example, one type of cone responds to the colour red. The other type of cone responds to the colour green. The third type of cone responds to the colour blue.

Amazing Eyes

We have been looking at these pictures during 1 minute and then we saw them everywhere.

http:// www.coolopticalilusions.com

Learn more about light and colours

http://www.odec.ca/projects/2003/kinga3a/public_html/introduction_to_light.html

http://videos.howstuffworks.com/hsw/6243-out-of-darkness-vision-video.htm

http://videos.howstuffworks.com/hsw/6243-out-of-darkness-vision-video.htm

VÍDEO

ASESORA DEL CFIE:
SUSANA RUBIO CANO