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Light and Sound wave problems PLEASE HELP!

  1. May 13, 2003 #1
    I have a few questions that I need assistance understanding and solving. I would greatly appreciate any help provided to me.

    1. A musical instrument is invented that consists of a can with length L and diameter L/6. The top of the can is cut out, and a string is stretched across this open end of the can. The tension in the string is adjusted so that the frequency of the fifth harmonic for the longitudinal sound in the air column in the can equals the frequency of the sixth harmonic for transverse waves on the string.

    - What is the mathematical relationship between the speed of the transverse waves on the string and the speed of sound waves in the air?

    - What happens to the sound produced by the instrument if the tension in the string is increased by a factor of four? (I would appreciate more in depth comment on this particular question)

    2. A convex spherical mirror with a focal length of magnitude 24.0cm is placed 16.0cm to the left of a plane mirror. An object 0.80cm tall is placed midway between the surface of the plane mirror and the vertex of the spherical mirror. The spherical mirror forms multiple images of the object.

    - Where are the two images of the object formed by the spherical mirror that are closest to this mirror, and how tall is each of them? Are the images real or virtual, inverted or upright?

    3. A luminous object is 5.2m from a wall. You are to use a concave mirror to project an inverted image of the object on the wall, with the image 4.00 times the size of the object.

    - How far should the mirror be from the wall, and what should its radius of curvature be and is the image real or virtual?

    Once again, I appreciate feedback/responses from anyone that can help me. Just to add; I have tried to solve number 1 in this post and got some figures for the two speeds. I tried to solve the second question but when I realized that the light wave keeps bouncing off the mirrors I was sort of at a loss as to how to completely answer the questions. So mainly I am asking for more focus to be put on the second question for the first problem and the second and third problems as a whole if it isn’t asking for too much. Thanks for the help once again.
  2. jcsd
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