Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Image formed from object at focal point of concave mirror

  1. Sep 10, 2015 #1
    The question posed: "An object is located to the right of a mirror that in concave in its [the object's] direction. If the object sits on the focal point of the mirror, what answer best describes the image formed?"

    Our class is united in the notion that as the rays would be parallel, intersecting only at infinity, no image is formed on either side of the mirror (or at infinity on both sides). Our textbook corroborates this, but our professor has only offered four answer choices:

    A. The image is to the left of the mirror and larger than the object.
    B. The image is to the left of the mirror and smaller than the object.
    C. The image is to the right of the mirror and larger than the object.
    D. The image is to the right of the mirror and smaller than the object.

    and maintains that the answer is B, which would indicate--to assume I've read the setup correctly--a virtual image, being to the left of and therefore behind the mirror, with a negative magnification. Does the solution lie in the wording of the question ("best describes") or are we all missing a key factor in our understanding of spherical reflecting surfaces?

    I'd call it a mistake on her part, but she seems entirely sure of herself and undergraduates are nigh-guaranteed to be outclassed in optics knowledge by a full-time optoelectronics researcher with a Ph.D in experimental solid-state physics. Really appreciate the help, folks!
     
  2. jcsd
  3. Sep 10, 2015 #2

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    Ask for a demonstration of the working.
    The model answer is correct for the mirror convex in the objects direction... may be a typo on the question.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Image formed from object at focal point of concave mirror
Loading...