Light

Pennie Machnick                Dirksen School
                               8601 W. Foster Ave.
                               Chicago, IL. 60656
                               312-792-8590
 
Objectives:

(Grades 4-6)
1.  Students will be able to calculate the angle of reflection and the angle of 
    incidence and discover that these angles are equal.
2.  They will discover that light disperses through a medium and a variety of 
    colors can be seen.  This will resemble a blue sky and sunset.
3.  They will discover that light refracts when entering different media.
4.  They will discover that light is pure energy.  

Materials:

1.  Aquarium, high intensity flashlight, Coffee Mate, mirror, protractor 
2.  prism, screen (use typing paper mounted on a desk size paper clip)  
3.  beaker, pencil
4.  box with any object inside 

Procedure:

1.  Fill an aquarium three fourths full of water.  Add about one half teaspoon 
of Coffee Mate to the water and mix this solution.  Place a flat mirror in the 
bottom of the aquarium.  Shine a high intensity light beam from a flashlight 
into the side of the aquarium toward the mirror.  Turn off the room light and 
view the angle of reflection and the angle made by the light to the mirror 
(angle of incidence).  Place a protractor along the base of the aquarium. 
Measure the angle of reflection and the angle of incidence.  The angle of 
reflection and the angle of incidence will be equal in each case. 
                 
2.  Using the same aquarium and solution, shine the high intensity light 
through the solution parallel to the base.  The water will appear blue like a 
blue sky because blue light disperses.  When the students view the light from 
the far end of the aquarium, the light appears orange like an orange sunset.  

3.  Fill a beaker half full of water.  Place a pencil into the beaker.  The 
pencil will appear to be broken at the point where the pencil meets the water.  
Explain that light rays are refracted at angles when they travel through 
different media. 

4.  Place any object inside a box.  Tell the students that you will hold up the 
object and they will get five seconds to view it after which you will hide the 
object and they will describe it.  On the count of three turn off the lights in 
the room and hold up the object.  Ask the students to describe the object.  They 
will say they can't.  Ask them why.  They will say there was no light.  Explain 
to them that light is pure energy.  Tell them that pure energy can only by used 
at that moment.  We will never have that particular light beam again.  Draw the 
light rays on the chalkboard to emphasize.