November the 5th

Hello classmates=] So yes, today in class we continued the The Nature of Light: Part Two topic by discussing Young's Experiment. But before we go there, we also corrected yesterday's homework questions (9-12 from the question booklet), so here are the answers to those questions...


9. You were asked to draw the wavelets at each of the places where the light rays intersect with the wave CD, so the blue curves that don't look very blue after upload are those wavelets...

10. In your diagram include...
a) the wave ray indicating the direction ofmotion of the reflected wavelet
b) a possible location of the wavefront
c) the correct location of the wavelet in relation to the wavefront
d) the angle of reflection

11. a) When waves move from deep water to shallow water, the wavelength of the wave would become smaller and the speed would decrease.
b) According to the wave theory, the speed of light is slower in an optically denser medium while the corpuscular theory states the opposite - speed is faster in the denser medium.

12. If we wanted to observe the diffraction of light as it passes through an opening, the opening should either be smaller or the same size as the wavelength of the lights used in order to observe the effect.


And that was it for the previous homework questions. Next, we read about and discussed Young's Experiment which can be found on pages 17-20 in the green booklet, so make sure you read about that. Part of what we discussed in class included the interference patterns produced by light, and it's pretty interesting, especially as explained by this video which we also watched in class... http://www.youtube.com/watch?v=DfPeprQ7oGc. And another site that further discusses light interference patterns: http://www.colorado.edu/physics/2000/schroedinger/two-slit2.html. Haha, yupp=]]



For homework tonight, just make sure you finish questions 13-15 in that same question booklet. Well that's basically all for today. I'm gonna wrap it up here... tomorrow's scribe will be Larlyn. Is that okay? Okaayy... See yah tomorrow guysss.

September 16, 2008 - Tuesday

So hello guys=] It's caaamy (Camy.. in case) and I am your scribe for today, thanks to Yvanne=[. Hah, I'm pretty clueless as to how to use blogger and all, so humor me please.

Today in class, Ms. Kozoriz started off by explaining the two types of wave interference:
Constructive Interference and
Destructive Interference

In case you weren't there or weren't really paying attention, I'll recap for you what you should have picked up from today's lesson.

First of all, wave interference - occurs when two or more waves act simultaneously on the same particles of a medium, resulting in a new displacement.

Constructive Wave Interference

This first type of wave interference occurs when two waves interfere with each other to produce a resultant displacement greater than the displacement that would be caused by either wave.
You can remember this because its title is logical to its concept - construct as in to build, so this is the type of interference that results in a higher amplitude, made up by the two pulses directly on top of each other.

In order to determine the new displacement of the particles, the Principle of Superposition is used. This principle states that the resultant displacement of a given particle is equal to the sum of the displacements that would have been produced by each wave independently. The two pulses can either be a crest and a crest, or a trough and a trough in order for constructive wave interference to happen.
In the example below, let's say that each pulse has an amplitude of 1 cm. As the two pulses approach each other, at the time interval of 1 second, they interfere and are directly on top of each other resulting in the maximum amplitude of 2 cm (the sum of the two waves).

Remember that these two pulses cannot be opposite as in, a crest interacting with a trough, vice versa. That, would result in a different type of wave interference. And you bet that this would be...

Destructive Wave Interference

This type of wave interference occurs when the resultant displacement is smaller (destruction!) than the displacement caused by one wave independently.

The diagram below is much like the one we drew in class today as an example of destructive wave interference. So using it (pulse A is the left pulse, pulse B is the right pulse), the two pulses are approaching each other. They both have an amplitude of 2 cm. At the third time interval, the two pulses are interfering with each other. Because these two pulses are equal in amplitude but opposite to each other, they cancel each other's displacement. This results a displacement of zero, causing the horizontal line that you see.

If you can't get anything out of my explanations then you can check out these sites for further clarification:
Constructive Interference - http://id.mind.net/~zona/mstm/physics/waves/interference/constructiveInterference/InterferenceExplanation2.html
Destructive Interference -
http://id.mind.net/~zona/mstm/physics/waves/interference/destructiveInterference/InterferenceExplanation3.html
annd hey! Ms. K mentioned this site and it's pretty informative, you should also check it out:
http://www.walter-fendt.de/ph14e/


After our little lesson of today, we were to move on to correcting last night's supposed homework, questions 7-14 from the blue booklet (Grade 11 Physics - Waves in One Dimension). However when Ms. K brought it up and checked to see who finished it, a much less than adequate amount of people completed it.=O. She then gave us the rest of class to work on that, along with the two worksheets, which we must all hand in tomorrow. I should put some emphasis on that.

Homework!!!
- Questions 7-14 from the blue booklet
- The two worksheets to hand in for tomorrow entitled Wave Characteristics and Wave Superposition.
- Study for the Waves in One Dimension Test that will be on Thursday, September the 18th!


Okay, that is all for today's scribe post! I'm sorry if it seems rushed (that's only because it was rushed) AND that it's quite late due to work, but I tried my beeest! And hey, look forward to tomorrow's scribe post which will be done by none other thaaan...
Lynel Pobre! - lynel (you're very welcome).

See yaahh everyone=]]