Where Will the Image Be Formed with Light Rays Perpendicular to a Plane Mirror?

Join the discussion
Ask a follow-up here, or get your own question answered by working scientists, mathematicians and engineers — people, not an autocomplete.
Real named experts · corrections over time · the nuance an AI answer skips
2 replies · 16K views
navneet9431
Gold Member
Messages
107
Reaction score
9
Screenshot_2019-02-04-18-03-44-235_com.hashlearn.now.jpg

Suppose light rays from an object fall perpendicular to the surface of the plane mirror.
Will the image be formed at +infinity(a virtual image) or -infinity(a real image)?

I will be thankful for help!
 

Attachments

  • Screenshot_2019-02-04-18-03-44-235_com.hashlearn.now.jpg
    Screenshot_2019-02-04-18-03-44-235_com.hashlearn.now.jpg
    16.1 KB · Views: 689
on Phys.org
In your diagram, the virtual image will be at ##+ \infty## (plus infinity).
There will also be a real image at ##- \infty## (minus infinity).

However, these terms (real and virtual image) are normally used with images that converge without going to infinity.

Normally, a plano mirror will only yield a virtual image - one that appears behind the mirror.
But in your drawing, you are showing the image originating from minus infinity - which is a special case.
 
Last edited:
  • Like
Likes   Reactions: navneet9431
.Scott said:
But in your drawing, you are showing the image originating from minus infinity - which is a special case.
That's by treating the plane mirror as the limiting case a concave mirror with radius approaching infinity, I think. For a concave mirror with finite radius, there is an object distance where the image position hops from - to + ∞ (and for many other optical arrangements).
Hyperphysics has some good diagrams of what happens with concave mirrors - just extend the idea to a mirror with infinite r.