What do you see? (don’t tell your partner just yet)

The Eye

Mr. PetriccioneLife Science

Look at the camera’s in the front…

• How do these work?

Cameras• Light passes through a lens and puts the

image on a piece of film, where it can be permanently seen.

The Eye

• Have you ever wondered how such a simple object can allow us to see everything around us?

How does the eye work?

• The world around us is projected into the eye in the form of visible light.

How does the eye work?

• The image passes through the cornea, which covers the lens.

How does the eye work?

• The image then is projected on the back of the eye, which is called the retina.

What do you notice?

• The image is flipped!

Why?

• What kind of lens is it?

There are two types of lenses

• Concave -the lens bends inward

• Convex -the lens curves out

So which lens is in the eye?

• A convex lens

So….

• This means the image gets flipped as it passes through the lens.

Why is this important?

• When we build and use the pinhole cameras, the photos will pass through a hole that acts as a convex lens.

So what does that mean?

• This means that the photo we get will be upside down.

• We simply flip the image.

• More on that in a few minutes….

But how come our world isn’t upside down?

• Our brain controls our eyes and flips the image!

Is this always the case?

• Actually, it is believed that when a baby is born, it sees the world upside down because its brain is not used to vision yet and has not been trained to flip everything.

How do we know our brain controls everything?

• Check out the these images….

This really isnt moving….

Wait…

• Our brain tries to see something that makes sense. If it doesn’t make sense, our eyes are told to adjust until we see something.

But how do we know?

• A famous study proved this!

More optical illusions

• Stare at the following image for 30 seconds….stare at the plus.

• Do not look away. Do not stare past the image

Count the black dots

What do you see…

How about now…