Using a mirror and a lens, an object and its image are made to coincide

  • #1
phantomvommand
238
37
Homework Statement:
A lens has a focal length of 0.3m. A plane mirror is placed 0.2m behind the lens. Where must an object be placed, for its image to coincide with its position?
Relevant Equations:
Ray diagrams
thin lens formula
Apparently, it must be placed at the focus (0.3m away from the lens). Why is this so?
 

Answers and Replies

  • #2
haruspex
Science Advisor
Homework Helper
Insights Author
Gold Member
2022 Award
39,164
8,487
Homework Statement:: A lens has a focal length of 0.3m. A plane mirror is placed 0.2m behind the lens. Where must an object be placed, for its image to coincide with its position?
Relevant Equations:: Ray diagrams
thin lens formula

Apparently, it must be placed at the focus (0.3m away from the lens). Why is this so?
If the object is at the focus, what can you say about the rays from a given point on the object after they have passed through the lens?
Follow their path on to the mirror and back through the lens.
 
  • Like
Likes phantomvommand
  • #3
phantomvommand
238
37
If the object is at the focus, what can you say about the rays from a given point on the object after they have passed through the lens?
Follow their path on to the mirror and back through the lens.
Won't the rays that emerge from the lens all be parallel to each other? But the rays hit the mirror at different points. How will the reflected paths then reconverge to form the image?
 
  • #4
phantomvommand
238
37
If the object is at the focus, what can you say about the rays from a given point on the object after they have passed through the lens?
Follow their path on to the mirror and back through the lens.
I see what you mean. Thank you very much
 

Suggested for: Using a mirror and a lens, an object and its image are made to coincide

Replies
7
Views
341
Replies
2
Views
564
Replies
10
Views
613
  • Last Post
Replies
12
Views
315
Replies
8
Views
390
Replies
12
Views
397
Replies
6
Views
383
Replies
26
Views
1K
Replies
3
Views
336
Top