Image formed from object at focal point of concave mirror

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SUMMARY

The discussion centers on the optical behavior of a concave mirror when an object is positioned at its focal point. Participants unanimously agree that no image is formed, as the rays become parallel and intersect at infinity. The professor's assertion that the image is virtual and to the left of the mirror (answer B) contradicts the established understanding, leading to confusion. This discrepancy may stem from a potential typo in the question regarding the mirror's curvature.

PREREQUISITES
  • Understanding of concave mirrors and their focal points
  • Knowledge of ray diagrams in optics
  • Familiarity with image formation concepts in spherical mirrors
  • Basic principles of virtual and real images
NEXT STEPS
  • Study the principles of ray tracing for concave mirrors
  • Learn about the differences between real and virtual images in optics
  • Investigate the mathematical equations governing mirror optics, such as the mirror formula
  • Explore common misconceptions in optics education and how to address them
USEFUL FOR

Students of physics, educators teaching optics, and anyone interested in understanding the principles of image formation in concave mirrors.

Max Matiauda
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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!
 
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The model answer is correct for the mirror convex in the objects direction... may be a typo on the question.
 

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