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Homework Help: 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 27, 2008 #2


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    Science Advisor
    Homework Helper

    Hi banana44! :smile:

    You've asked a very long question!

    And you know you're suppposed to show how far you've got, so that we know how to help you. :smile:

    Let's start with 4 and 5:
    What is the definition of a real image?

    What is the definition of a virtual image?

    Then just answer 5 in ordinary language. And draw a diagram as part of your answer.

    Have a try! :smile:
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