# Physics Quizzes

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Will copies of the quizzes, or at least their solutions be posted?

Quiz 10:

1) (EM wave traveling in x-direction) The cross product of E and B will give you the direction the wave is traveling, so the magnetic field must be in the z-direction at this instant.

2) (Critical Angle question) If theta becomes too large, light will not be able to leave the glass. This occurs at the critical angle which depends on the indices of refraction of the two medium in question. For this setup, the angle this occurs is 41.8 degrees.

3) (Laser light "sword") The light saber is made of light and will travel the same path light will travel, so it should be pointed at where the person sees the fish.

4) (FM radio) Radio waves travel at the speed of light, so we are able to find the wavelength knowing the frequency: lambda = 3.14m

5) (single or double slit) a) the first pattern is a typical double slit pattern. b) the second pattern is a typical single slit pattern

6) Intensity transmitted through a polarizing disk is decreased by the Cos Squared of the angle. 69.0 degrees is the answer

Quiz 9:

1) (wavelength of standing wave) IF the tension is quartered, the wave velocity is halved. Since the frequency remains constant, the wavelength must be halved as well.

2) (closed pipe) The difference between two natural frequencies of a closed pipe will be twice the fundamental frequency because all odd harmonics are missing in the closed pipe. The answer is then 50 Hz

3) (standing wave pattern) The pattern shown looks like a standing wave on a string fixed on both ends. Displacement waves at open ends of pipes should be maxima, not minima.

4) a) Doppler effect with source moving away

b) Doppler effect with source moving towards

c) Beat frequency is simply the difference between the two frequencies heard
answered Dec 9, 2014 by (2,140 points)
edited Dec 10, 2014 by jcf1559