• Support PF! Buy your school textbooks, materials and every day products Here!

Optics - For what distance must we focus our eyes to see this image

  • Thread starter Kathi201
  • Start date
  • #1
40
0
An object is placed 1m in front of a plane mirror. An observer stands 3m behind the object. For what distance must the observer focus his eyes in order to see the image of the object?
 

Answers and Replies

  • #2
Mentallic
Homework Helper
3,798
94


5 metres? Was that all there is to the question?
 
  • #3
40
0


Yeah that is all the question was. How did you figure that out?
 
  • #4
tiny-tim
Science Advisor
Homework Helper
25,832
249
An object is placed 1m in front of a plane mirror. An observer stands 3m behind the object. For what distance must the observer focus his eyes in order to see the image of the object?
Hi Kathi!

Hint: for a plane mirror, where is the image in relation to the object? :smile:

(Hi Mentallic: please don't give out answers! :wink:)
 
  • #5
40
0


Do you mean that it is in an angle? I am not quite sure of the answer you are looking for
 
  • #6
tiny-tim
Science Advisor
Homework Helper
25,832
249
Do you mean that it is in an angle? I am not quite sure of the answer you are looking for
Mirrors are like lenses … every object has an image.

For a plane mirror, where is the image of an object? :smile:
 
  • #7
40
0


The image is located in front of the mirror. Isn't the image distance equal to the object distance. Thus it would be 3m
 
  • #8
40
0


Ok so now that I am thinking about, is the image behind the mirror or in front. I am starting to think it is behind?
 
  • #9
tiny-tim
Science Advisor
Homework Helper
25,832
249
Ok so now that I am thinking about, is the image behind the mirror or in front. I am starting to think it is behind?
Yup, the image is definitely behind the mirror! :biggrin:

(It's a virtual image: the rays of light "from" it don't actually get anywhere near it, do they? :smile:)

Sooo … how far away from the observer is the image of that object she's standing behind?​
 
  • #10
40
0


The object is 1m away and the person is 3m away so it would be 3m +1m + the 1m behind the mirror so it would be 5m.
 
  • #11
tiny-tim
Science Advisor
Homework Helper
25,832
249
That's it!

Any questions? :smile:
 

Related Threads for: Optics - For what distance must we focus our eyes to see this image

  • Last Post
Replies
2
Views
4K
Replies
2
Views
6K
Replies
1
Views
2K
  • Last Post
Replies
1
Views
9K
Replies
1
Views
826
Replies
3
Views
12K
Replies
9
Views
2K
Top