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Light rays / mirror equation.

  1. Apr 24, 2008 #1
    hey guys i really need help with these problems.I am not good with physics at all, i just need this to graduate . I really don't understand it and my teacher isnt much help. If anyone can help me out with this i would really appericiate it.
    Thank you.

    1.Why are parallel light rays used to show the difference between regular and diffuse reflection?
    2.List some situations where the letters on signs are reversed. Explain why it is being done.
    3.As the object is moved along the principle axis toward the vertex of a concave mirror, the type of image changes. Where does the change in type of image occur? Explain why, in terms of the path of the light rays.
    4.Explain the difference between a real and virtual image.
    5.Explain why concave mirrors can produce real or virtual image, but convex mirrors can produce only virtual image.
    6.Concave mirrors are used in searchlights and solar ovens. Draw two diagrams to show the path of light in each case, and explain why these two applications demonstrate the principle of the reversibility of light.
    7.Describe the similarities and differences of the properties of the images formed in a plain mirror and a convex mirror. Why are convex mirrors used for security purposes in stores, rather than plane mirrors?
    8.Usha wants to take a picture of her own image in a plane mirror. At what distance should the camera lens be focussed if it is positioned 2.3 m in front of the mirror?
    9.A ray of light strikes a mirror at an angle of 550 to the normal.
    a)What is the angle of reflection?
    b)What is the angle between the incident ray and the reflected ray?
    10.A ray of light strikes a mirror at an angle of 570 to the mirror surface. What is the angle between the incident ray and the reflected ray?
    11.What is the angle of incidence if the angle between the reflected ray and the mirror surface is 340?
    12.Light is shining on to a plane mirror at an angle of incidence of 270. If the plain mirror is tilted such that the angle of incidence is reduce by 80, what will be the total change in the angel of reflection from the original reflected light?
  2. jcsd
  3. Apr 24, 2008 #2
    The mutual silence here speaks volumes...you need to read your textbook! :)
  4. Apr 24, 2008 #3
    yeah but if someone doesnt understanding a subject; doesn't matter how much they read the textbook.
    Isnt that why this site was made? to help people understand the work ?
  5. Apr 24, 2008 #4


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    Science Advisor
    Homework Helper

    The homework forums are to help people who are stuck on problems - not just an answers in the back generator. Here are some hints.

    In diffuse reflections the light bounces off at all angles.

    Do FIRE engines in your country have ERIF painted on the front? How do you see vehicles behind you in a car?

    Look up the diagram for a concave mirror showing rays from in front/at/behind the focus.


    To get a real image rays must converge - draw the rays hitting each type of mirror.

    Focus a paralel beam at a point or produce a parralel bema from a point.

    What range of angles can you refelct from the mirror

    The image is the same distance behind the mirror that the object is in front.
    I assume the extra 0 on each of these is a deg symbol?
    All you need to know is that if you draw a line from the mirror outward at 90deg to the surface (called a normal) the light reflects with the same angle from this line that it had when it arrived - bit on the other side.
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