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).
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=]]
2 comments:
You did a great job in summarizing what was covered in class today.
I liked that you cited some websites on interference.
woo!!!!!! go camy!!!! tottaly forgot aabout the test thnxs :P awsome post :):P
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