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Post by blackcat007 » Sun Jul 26, 2009 1:29 pm


ok this question is soo ambiguous.. isn't it obvious that one ray will be reflected with a phase shift of pi for the first air glass interface and the other will go pass the first interface and then get reflected from the second air glass interface with a pi phase shift.. and thus simply 2t=m(lambda).. ??

in comparison to these old tests 0177 has no ambiguity.. so is ETS revising their and improving their tests?? can i expect to get a test free from ambiguity this nov 7th :D ?

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Re: 9677#82

Post by WakkaDojo » Thu Aug 27, 2009 8:43 am

The pi phase shift only occurs when reflecting off of a medium with a higher refractive index than that which the light is traveling through.

For instance, suppose we have | glass | air |. If light is traveling from glass to air but reflects off of the surface, the reflected wave in the glass does not experience the sudden phase shift. However, if it is traveling from air to glass, the portion of light that reflects off of the surface will undergo a phase shift of pi.

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