concave convex lens

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					     LIGHT AND LENSES
             by
        Ms. Mendoza
5th Grade Lincoln Elementary
WHAT HAPPENS TO LIGHT?
When light strikes an object, two things
can happen:

     Reflection       Refraction
                 REFLECTION
Reflection occurs when light
bounces off objects. How
much reflection depends upon
how even the surface is. If the
surface is rough, the light
scatters. If the surface is
smooth and flat, the light will
bounce off it at equal
angles. That is why a flat
mirror reflects a good likeness
of the object being reflected.

                                  Click above
REFRACTION
Refraction occurs
because light bends.




 Click for more information on
 refraction
 How does this relate to lenses?
A lens is a device that bends light.
A lens is a piece of transparent
        material.
If it is transparent, you can see
        through it.
It is usually made of glass and
        has at least one
curved surface.

There are two types of lenses:
1.   Concave
2.   Convex                            Click the
                                       picture above
                                       for more
                                       information
                                       about lenses.
Concave and Convex Lenses
Look at the convex and concave lenses
below:
The curved surface/surfaces of a lens bends the light.
Notice the paths of light of the convex and concave lenses shown below.
           Convex Lenses
A convex lens is thicker in the middle.
A convex lens bends light rays so that they
meet at a focal point. This means that the
Light rays are converging.
            Concave Lens
A concave lens is thinner in the middle.
A concave lens bends light rays to make
them spread out. This means that the
light rays are diverging.
         Answer the questions about
           reflection and refraction
1. _____________ occurs when light bounces off an object.

2. _____________ occurs when light is bent.

3. When light strikes a surface that is rough, the light will ______________ .

4. When light strikes a surface that is smooth, the light will bounce off at equal
    ______ .

5. What type of material is a lens?
   a. transparent
   b. translucent
   c. opaque

6. The path of light through a concave lens is
   a. not directed to a single focal point
   b. directed to a single focal point

7.The path of light through a convex lens is
  a. not directed to a single focal point
  b. directed to a single focal point

				
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