Alex's Post, October 1, 2008

Hey everybody! It's Alex :) I've never done a blog before so sorry if this sucks. Anyway today in class we corrected the review and did a sheet on the overhead. I'll start with the review.

Here are my crappy examples of question 1:




Make sure your reflected wavefronts are the same length and distance from each other as the incident wavefronts!









Make an imaginary dot behind the barrier the same distance from the barrier as the original dot. From this dot draw you reflected wave rays.


Question 2) reflected wavelength= 1.6 cm

Question 3) a) n=o.75
b) Shallow Water: wavelength=2.07 cm
Deep Water: wavelength=2.75 cm
c) Angle of incidence= 32 degrees

Question 3 diagram)













Question 4) The wavelength of deep water is equal to 4.5 cm

Vs* lambda d= Vd* lambda s which equals lambda d= Vd* lambda s/Vs: this is the equation I used to find this.

With numbers it would look like:
lambda d= (1 cm/s) * (3 cm)/ (2/3 cm/s)


Question 5) The wavelength of 1.4 m would have the greatest diffraction because the longer the wavelength the greater the diffraction.

Question 6) The frequency of 200 Hz would have the greatest diffraction because the smaller the frequency the longer the wavelength and the longer the wavelength the greater the diffraction.

Question 7) Sorry I cannot draw this!
b) The perpendicular bisector indicates an area of constructive interference.
c) P2 is located on nodal line 2.
d) | PnS1-PnS2|=(n-1/2)*lambda: lambda equals 3 cm
e) 3.5 * 3 cm/ 1 lambda= 10.5 cm

Question 8) a) |PnS1- PnS2|=(n-1/2)*lambda: lambda equals 1.6 cm
b) f= V/ lambda
f= 3.44 Hz

So that is the review.

The over head sheet answers are:

1) The red arrows represent light rays.

2) The angle of incidence for light entering the glass is 60 degrees.

3) The angle of refraction for light entering the glass is 34.5 degrees.

4) The value of the angle of incidence leaving the glass is 34.5 degrees.

5) The value of the angle of refraction for light entering water is 40.5 degrees.

6) I would expect the glass to have a greater index of refraction because it's angle is closer to the normal which means it is denser which means it has a greater index of refraction.

7) n= Sin 60 degrees/ Sin 34.5 degrees= 1.5: index of refraction for glass

8) n= Sin 60 degrees/ Sin 40.5 degrees= 1.3: index of refraction for water

9) The light will travel faster through water.


So that is my post, good luck on the test tomorrow I hope everyone does well. And to everyone who's done a post already you should give yourself a pat on the back, scribing is hard work! I don't know who to pick for scribe, I don't really know how it works so I'll pick the wonderfully smart Katie N.
Bye! See everybody tomorrow :)