Low to High Optical Density

by   Posted on November 26, 2010 in Uncategorized

Background Information
Light bends when travelling through two objects with different optical density.

Aim
To find out whether the light bends towards or away the normal from low to high OD objects.

Hypothesis
When light travels from a low OD to high OD, it bends towards the normal.

Apparatus and Materials
1) A light box
2) Power pack
3)Ruler
4)Paper
5) Pencil
6) Protractor

Safety
There’s no safety procedures.

Method
Variables:
 Independent- The angle of incidence.
 Dependent- The direction the light is bended towards, the angle refraction.
 Controlled- Light output.

Step by step:
1)Plug lightbox to power pack.
2) On light box and shine at perspex’s normal, not perpendicularly.
3) Compare the angle of incidence to the angle of reflection, which angle is bigger?
4) Write results.
5) Repeat 2,3,4.

OD

Results

Angle of Incidence  44 63 6
Angle of Refraction 25 37 3

Discussion
What: When light travels from air to perspex, it always bends towards the normal.
Why: The angle of refraction is always lesser than the angle of incidence.
Evaluation
Reliability: Three angles of incidences were collected to make this reliable.
With one  angle nearest to and one furthest from the normal as possible while the third one in between.
Using a light box makes the light beam considerably focused makes the results more accurate as well.

Strengths: By placing the paper under the perspex, it was easy  to change the angle of incidence without
adjusting it again so it shines on to the normal. Using the pencil and ruler, it was easy to draw the light beam
path  and then measure it using a protractor.

Improvements: If there was a laser pointer that shows not only it’s start and end point but also it’s path,
it will be much more accurate on drawing the line of the light as white light expands the further it goes.
Using a compass would also making drawing the line of light much more accurate as it will be more convenient.

Validity: Overall, it is a fair and accurate test however, most of the measurements are off by 1-4 degrees. This
could be resolved.

Conclusion
The hypothesis is supported as no matter what the angle of incidence is, the angle of refraction is always lower.

 

Isaac Newton

by   Posted on November 25, 2010 in Uncategorized

Isaac Newton
I’m borned in England at 1643 as prematured child three months after my father’s death.
I lived in Woolsthorpe Manor.
There was once when I was investigating the bending of light, I made an accidental discovery that light was made of
a spectrum of colours. This was when I made the theory of color. Although many other scientist did a similiar experiment, i discovered
something more. Refracting the light through the prism at different degrees shows difference in colour. I called this the refrangibility.
Colours of the Optical Spectrum

Background Information
White light is believed to show rainbow-like effects when being bended by certain objects
like glass and water.

Aim
To investigate whether the myth (white light is made of many optical colours combined)
is true or false.

Hypothesis
White light will be dispersed by a prism into a colour spectrum.

Apparatus & Materials
A prism, a magnifying glass, sun light

Safety
-
No safety precautions required-

Method:

Independent variables
-
No independent variables-

Dependent variables
Result of the light passing through a prism.

Controlled variables
-No controlled variables-

Step by step
1. Wait for the sun to be at it’s peak to get best results.
2. Use a magnifying glass to focus sun light into a light beam.
3. Place the prism in front of light beam.
4. Record the results

Diagram
Colour Spectrum Diagram

Results
Colour spectrum was created after sun light passed through the prism.

Observations
When the colours are dispersing, at the center of the colour spectrum  ray closes  to the prism seems
to be white. The colours starts to split when they are a little further than the white part. This observation seems to bring me to another hypothesis. If the colour spectrum is to pass through a second prism, it will combine th

e colours back into a single, white light.

Discussion:

What
White light, after passing through a prism disperses into a colour spectrum.

Why
The light is bended, showing its other colours.

Evaluation:

Reliability
It was very reliable as this is the nature of light and not rocket science. Nothing will change if the experiment was to be done in a similiar but not exact way.

Strengths
Using the magnefying glass to focus the sun light gives a better, clearer result than just the sun light.

Improvements
Get a light box and using it will provide a much more accurate results than relying on the sun.
The light beam will also be more focused than the sun’s without any magnification.

Evaluating validity of method.
The experiment was a success as even though is a complicated result we are looking for,
the material and the method is simple. It could be improved if lightbulbs were already invented.

 
 
3rd July 1666,

White light seems to be made of many different colors combined or Spectrum of Colours (SC).
Shining white light into a prism seems to split the light into Spectrum of Colors.
I shall attempt to combine the spectrum of colours into white light again

Prisma-lightSpectrum-goethe

15th August 1666,

Who would have thought placing another prism would combine the SC back
to a white light? This experiment has supported my theory

What happens when a light passes through 2 Prisms

Isaac Newton discovered that white light is made up of a spectrum of colors, that when blended together produce the white light. He showed by use of a prism that white light can be split into a spectrum of colors and then used a second prism to show this spectrum can then be rejoined to produce white light. Newton … theorized that light was composed of particles but had to associate the property of light with waves in order to explain refraction of light.

Reflection

by   Posted on November 20, 2010 in Uncategorized

 Aim: To find out the angle of incidence equals the angle of relection

Hypothesis: The angle of reflection equals the angle of incidence

Apparatus& Material: Lightbox, powerpack, paper, protactor, mirror, pencil, ruler.

Safety, Don’t touch the light bulb, don’t shine light directly into your eyes.

Method:

1) Plug in power pack
2) Connect light box to power pack
3) Cover all light box sides with something except the font.
4) On the light box.
5) Put a mirror on top of paper, 10cm away from light.
6)Change the angle the light is shining on to the mirror
7)Measure the angle of incidence and reflection using a protractor
8)Write results
9) Repeat 6,7,8

Variable:

Independent variable: Angle of Incidence- the direction the mirror is facing.
Dependent variable: Angle of Reflection
Controlled variable: Distance between light source and mirror. Light output.

   
Diagram for reflection of light
Diagram for reflection of light
NOT SHOWN IN DIAGRAM: piece of paper under mirror used for measuring normal.
  Angle of Reflection          
               
Angle of Incidence 35 50 70 30 50  
Angle of Reflection 30 53 68 29 49  
               
 
Science Chart
 
Discussion
what:  the Angle of Incidence always equals the Angle of Reflection
why: No matter how much degree the light was shone to the mirror was changed,
         the angle of the light that was reflected always remained the change to be the same as the Incidence.
 
Evaluation
Reliability of data: Not very reliable as results of the angles is never exactly the same because of my
        human error in measuring the angles. Experiment wasn’t repeated enough to determine that
angles of Incidence and Reflection are 100% the same.
 
Identify and explain two strength of experiment: A piece of paper was placed under the mirror to
    accurately draw the normal on and a light beam can be precisely aimed to the normal.
Rotating the paper makes it easy to change the angle of Incidence without positioning the mirror and
the normal again.
 
 Suggest and explain two improvements: Get a compass to be more precise on
 drawing the line of Incidence  and the line of Reflection.
Have a stronger light from the light box to improve visibility of light beam and it’s ‘Expanding’
might be reduced.
Evaluate validity of method: The method is basic and can be improved as stated above in numerous ways.
Although current data collected is sufficient to prove the hypothesis,
 more data also needed to be collected to support the hypothesis.
Conclusion: The hypothesis was supported, the angle of reflection always changed when the
angle of incidence was changed to be the same.  
 

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by   Posted on November 9, 2010 in Uncategorized

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