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Eyes

Eyes. D. Crowley, 2008. Eyes. To know how our eyes are developed to allow us to see the world around us. Shadows. In a theatre a clown is performing. A powerful spotlight shines onto the stage, creating a black shadow behind the clown that the audience can see…. What is the light source?

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Eyes

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  1. Eyes D. Crowley, 2008

  2. Eyes • To know how our eyes are developed to allow us to see the world around us

  3. Shadows • In a theatre a clown is performing. A powerful spotlight shines onto the stage, creating a black shadow behind the clown that the audience can see… • What is the light source? • Explain how the shadow behind the clown is formed… • Explain how light rays from the spotlight reach the audience, so that they can see the clown…

  4. Shadows • (1) What is the light source; (2) Explain how the shadow behind the clown is formed; (3) Explain how light rays from the spotlight reach the audience, so that they can see the clown • The light source is the spotlight • Light shines from the spotlight. The ray of light cannot pass through the clown (who acts as a barrier). As light travels in straight lines it cannot bend behind the clown, so a shadow forms where no light reaches • Light rays reach the clown, and reflect from him. These rays enter the eyes of the people in the audience, so they see him!

  5. The Eye • We see objects because light reflected from them enters our eyes • The light from luminous objects such as stars and lamps may enter our eyes directly • Objects which do not make their own light are non-luminous, but we can still see them if light from a luminous object reflects or scatters off them into our eyes A ray diagram, showing a luminous object (bulb) and non-luminous object (battery)

  6. The Eye Copy a diagram of the eye, and label the main parts

  7. The Eye • Retina - the light-sensitive part of the eye, covered in light receptors called rods and cones • Optic nerve - carries impulses from the light receptors to the brain • Lens - focuses light onto the retina • Pupil - the hole in the iris where light passes through

  8. The Eye • Suspensory ligaments - control the shape of the lens, along with the ciliary muscle • Ciliary muscle - controls the shape of the lens, along with the suspensory ligaments • Cornea - refracts (bends) light into the eye • Iris - changes the shape of the pupil to control how much light enters the eye

  9. Pinhole Camera • Cameras work in similar ways to eyes. The simplest kind of camera if a pinholecamera • It does not have any lenses, but a small hole made with a pin lets light in, which forms an image on the back of the screen • The hole at the front can be made bigger or smaller, controlling the amount of light which gets in • Your eyes work like this too, where the pupil gets smaller or bigger depending upon the amount of light

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