Kathi201
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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?
Optics - For what distance must we focus our eyes to see this image
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5 metres? Was that all there is to the question?
Kathi201
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Yeah that is all the question was. How did you figure that out?
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Kathi201 said:
Hi Kathi!
Hint: for a plane mirror, where is the image in relation to the object?
(Hi Mentallic: please don't give out answers!
)
Kathi201
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Do you mean that it is in an angle? I am not quite sure of the answer you are looking for
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Kathi201 said:
Mirrors are like lenses … every object has an image.
For a plane mirror, where is the image of an object?
Kathi201
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The image is located in front of the mirror. Isn't the image distance equal to the object distance. Thus it would be 3m
Kathi201
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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?
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Kathi201 said:
Yup, the image is definitely behind the mirror!
(It's a virtual image: the rays of light "from" it don't actually get anywhere near it, do they?
)Sooo … how far away from the observer is the image of that object she's standing behind?
Kathi201
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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.
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That's it!
Any questions?