Archive for April, 2011

Diffraction

1

Diffraction is the bending of waves around obstacles, or the spreading of waves as they pass through an opening, most apparent when looking at obstacles or wavelengths having a size of the same order of magnitude as the wavelength. Typically, the smaller the obstacle and wavelength, the greater the diffraction. Taken to the extreme, when a wave is blocked by a small enough opening, the wave passing through the opening actually behaves like a point source for a new wave.

You can observe diffraction quite easily… I’m sure you’ve heard a noise from a room with an open door even when your ears aren’t in a direct line from the sound source… this is a result of diffraction of the sound waves around the door opening (along with some reflection of sound as well).

Thomas Young’s Double-Slit Experiment is a famous experiment which utilized diffraction to prove light has properties of waves. Young placed a single-wavelength light source behind a barrier with two narrow slits, allowing only a small portion of the light to pass through each slit. Because the two light waves travel different distances to the screen on which they are projected, you can see effects of both constructive and destructive interference, phenomena that occur only for waves!

Question: The spreading of waves into the region behind an obstacle is known as _______.

Question: Which wave phenomenon is represented in the diagram?

Castle Learning Review Assignments

0

As we prepare for our comprehensive Regents examination in June, it is important to make sure we are up to speed on material covered throughout the entire year. Toward that end, we will undertake a series of seven Castle Learning review assignments consisting of 50-60 multiple choice questions on each of the major topics we have covered this year. These topics correspond to the short review podcasts available on iTunes. I would recommend viewing the appropriate review lessons before tackling the Castle Learning assignments. Then, take the Castle Learning assignments with your reference table, the calculator you will use on the Regents exam, and your notebook handy.

Each assignment is worth 50 to 60 points, with second chance correct scores counted for full credit! These are weighty assignments, with distinct opening and closing dates. Because these are being provided well in advance of due dates, you should have opportunity to plan your time accordingly. No credit will be given for late assignments or submissions, regardless of attendance or illness issues.

Assignments and Review Schedule is as follows:

 Assignment Podcasts Open Close Units Vectors Scalars R01 4/29/2010 5/6/2010 Kinematics R02,R03 5/6/2010 5/13/2010 Dynamics R04,R05 5/13/2010 5/20/2010 Momentum and WEP R06,R07,R08 5/20/2010 5/27/2010 Electricity and Magnetism R09-R12 5/27/2010 6/3/2010 Waves and Optics R13,R14 6/3/2010 6/8/2010 Modern Physics R15 6/8/2010 6/14/2010

Please take these assignments seriously, and be diligent in your planning and submissions. This is a large portion of our fourth quarter grading, and is an excellent opportunity to put yourself in position for achieving an optimal score on the Regents Physics Exam!

0

0

0

Go to Top