Who am I?

My name is christiaan huygens. I was born at the  Hague, Netherlands on April 14, 1629. I am now living in Den Hang with my family.So far, i have invented various things , for example, advanced pendulum clocks, 2 lense eyepieces, and long air telescopes of up to 250 feet focal length. In 1656, I derived the conservation of momentum law, and  in 1659, I established the idea of centrifugal forces. Now, i have interests about light. Even the greatest scientis Newton could not manage to explain the movements of parricles in light in details. That is why it is very challenging and i ll give everthing for the success.

Reflection of light

Background information

Objects can be seen by the light they emit, or, more often, by the light they reflect. Reflected light obeys the law of reflection, that the angle of reflection equals the angle of incidence. Moreover, we can see objects due to the reflection.

 

Aim

To find out whether angle of incidence and angle of reflection are same.

Hypothesis

I guess that the angle of incidence and the angle of reflection are not same because the patterns of reflection are unpredictable.

Apparatus and materials

In order to do this experiment, we need device that includes light. We also need the device which works as a switch and helps us control the power of light. Rather than those important things, it is required to have paper, pencil, ruler and protractor to measure the angles.

Safety

The experiment we are going to do is very safe. There will be no hazardous circumstances unless you touch the hot light bulb with your hands or touching the electrical devices such as switch with your wet hands. Everything will be safe.

 

 

 

Method

Independent variable: the light ray from the device

Dependent variable: the size of the angle when the light reflects from the mirror at the different angles.

  1. You have to place the device in the dark and make light ray straight.
  2. Place the mirror to check whether light ray bends its direction.
  3. You must draw the normal on the paper to ensure that you can notice the reflection of light easily.
  4. Now if everything is ready, you can measure the angles of incidence and angles of refraction by replacing mirror to different places of by changing the light ray.

 

Can you see the reflected light from the first picture above? The angle was thirty degrees. When you place the light ray to the opposite side, the angle was same.

( I could not get the picture to show the statement “angle of incidence and angle of refraction are same” thus, I had to get one from the internet.)

 

 

 

Results

Angle of incidence

Angle of reflection

10°

10°

30°

30°

50°

50°

70°

70°

 

Discussion

In general, the angle of incidence and the angle of reflection are always same if experience is done on the smooth surfaces like mirrors. I think lights always reflect on surface with fixed patterns. I have noticed that the incident ray reflect back precisely when there is a smooth surfaces.

Evaluation

I think I have not collected enough information and data, for example, I did not take appropriate photos. That’s why I had difficulties to choose the pictures on my report. Moreover, I have failed to discuss the experiment specifically. But at least, i have shown clear results of the experiment as I planned. I repeated measuring angles over three times, and it assisted me to get accurate results. If i had taken more photos to prove my statement it would have been better. Although my methods of experiment helped me to get the precise results, they were not enough as they were not in details. They are not explained well. Starting the experiment a bit later than other students gave me sort of pressure and it affects me badly as well. Next time, I will put more efforts and time on the report to ensure everything is satisfied.

Further

I have come up with a question while i was doing this experiment: what will happen to the light ray if it bounces off from rough spaces. Will it be bouncing off in patterns? If i have a chance to do an experiment on this, i would be really interesting.

Conclusion

My aim was to see whether the angle of incidence and angle of reflection are always same. I managed to find out the result through the experiment. It is: angle of incidence and angle of reflection are same, unlikely from my hypothesis.

Refraction of light

Background information

Refraction is the bending of a wave when it enters a medium where its speed is different. The refraction of light when it passes from a fast medium to a slow medium bends the light ray toward the normal to the boundary between the two media.In 1621, a Dutch physicist named Willebrord Snell (1591-1626), derived the relationship between the different angles of light as it passes from one transparent medium to another. When light passes from one transparent medium to another, it bends according to Snell’s law which states:
Snell’s Law- N1 Sinθ1 = N2 Sinθ2

Aim

To find out whether the light ray refracts with regular patterns through the different medium and to see whether the angle of refraction and the angle of incidence are equal.

Hypothesis

The light ray will be refracted with the regular rules and the angles of refraction and incidence will be equivalent.

Apparatus and materials

In order to do this experiment, we need device that gives out the light. We also need the device which works as a switch and helps us control the power of light. Rather than those important things, it is required to have paper, pencil, ruler and protractor to measure the angles. Also you must prepare different types of solid figures that will act as mediums (interfaces).

Safety

The experiment we are going to do is very safe. There will be no hazardous circumstances unless you touch the hot light bulb with your hands or touching the electrical devices such as switches, with your wet hands. Everything will be alright if we avoid doing careless things.

Method

Independent variable: the angle of incidence
Dependent variable: the angle of refraction
Controlled variable the angle of incidence and the light ray(?)

1. Set up the apparatus for the experiment,
2. Place one of the solid figures in front of the light ray.
3. Measure the angle of incidence.
4. Measure the angle of refraction.
5. Repeat the same thing about 4 times
6. Compare the angles of both incidence and refraction whether they are
equal.
7. Try the experiment with different types of solid figures.
8. See if you can perceive any rules or patterns applied when light rays are refracted.

Results

Angle of incidence Angle of refraction
10° 5°
30° 17.5°
50° 31°
70° 42°

Observation:

1. No specific rules or patterns have applied in the experiment 2. 2.Angle of incidence and angle of refraction are not same.

Discussion

In general, the angle of incidence and angle of refraction are not same no matter which mediums light went through. There are no fixed patterns or rules when light is refracted but I have perceived that the angles of refraction were less than angles of incidence. I think it was because the density of medium affects the light ray. Unlikely from the experiment of reflection, we made light ray went through the solid figure, not the plain ones in reflection. That’s why there can’t be exact rules.

Evaluation

I think I did slightly better than the previous report. I managed to give facts and steps in details. I got what I wanted to know and it was successful. But again, there were not enough visual effects like photos and statistics to support my experiment. Failure to test Snell’s law was my biggest mistake. I could not find methods to prove the equation. This is the result of underestimating the stuff. Next time I will be more considerable to accomplish the task perfectly, never forget to put as many visuals as possible too. Although there is still room for improvements, I determine that the task has done quite satisfied.

Further

I want to do an experiment on the Snell’s law. As I failed to prove it this time, I hope to have another attempt. That might be very challenging and interesting. Just want to check out how the equation applies to the refraction.

Conclusion

The angle of incidence and the angle of refraction are not same and there are no special patterns or rules applied when light ray refracts.

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