Transcript Now You See It!

Now You See It
Marion White and Alex Treser
Period 8/9 AP Physics 1
Types of Telescopes
Refracting telescopes work by using two lenses to focus the light and make it look like the
object is closer to you than it really is. Both lenses are in a shape that’s called 'convex'. Convex lenses
work by bending light inwards (like in the diagram). This is what makes the image look smaller.
Reflecting telescopes, on the other hand, don’t use lenses at all. Instead, they use mirrors to
focus the light together. In this case, the type of mirror that they use is a concave mirror. Mirrors of this
shape also accomplish the goal of bending light together, except that they do it by reflecting the light
instead of bending it as it passes through (like lenses do)
“Object are Closer Than They Appear”
Light bounces off the flat surface, the angle of
the reflected light is equivalent to the angle at
which it struck the surface. The focal pointwhere the incoming light strikes the surface.
Passenger side mirror is usually convex which
extends the focal point so that the light striking
the curved surface from a wider swath of angles
all converge at the same focal point and then
bounce into your eye.
Wider focal point compresses the reflected
image which make the objects appear smaller.
Focal Length
http://www.education.com/sciencefair/article/upside/
Inverted L with lenses and flashlight
http://www.education.com/science-fair/article/upside/
Why?
Magnifying glasses are made of
convex lenses. A convex lens makes
objects look larger because it
disperses light. When objects are
magnified, they are within the focal
length of the magnifying glass. The
focal length is the distance between
the center of the lens and its focus,
the point where an object can be
viewed clearly through a lens.
Why can’t we see far away?
As an object gets further away less of its light will reach your eye. The image takes up less space on your retina (the light-sensitive
tissue at the back of your eye), making the image smaller. This makes details of the image harder to see.
To make a distant object appear brighter and larger, we effectively need a bigger eye to collect more light. With more
light we can create a brighter image, we can then magnify the image so that it takes up more space on our retina.
The big lens in the telescope (objective lens) collects much more light than your eye can from a distant object and
focuses the light to a point (the focal point) inside the telescope.
A smaller lens (eyepiece lens) takes the bright light from the focal point and magnifies it so that it uses more of your
retina.
Mirror Equation
Magnification Equation
di= image distance
f = focal length
d0= object distance
d0 = object distance
I= image size
di= image distance
O= object size
Convering lense
Divergent Lens
Two Converging Lenses
Converging and Diverging Lense