Naked Science Forum
General Science => General Science => Topic started by: katieHaylor on 31/07/2017 16:35:06
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Farhan asks:
When we look at an object 'in' a mirror, do our eyes focus on the reflection of the object or the mirror?
What do you think?
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A flat mirror is merely reflecting the light waves that hit the surface back at the same angle at which they arrived. Therefore you'd need to focus as though looking at the reflection for real for it not to appear blurry. A curved reflective surface, however, like a satellite dish, focuses the light to a point so it behaves like a lens.
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When we are cleaning the mirror, we focus on the mirror itself.
When we look at ourselves in the mirror, our eyes focus on a point twice as far away as the mirror.
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you can test this for yourself by holding two objects (one in each hand) at different distances from the mirror (I would recommend one hand between you and the mirror, and one hand behind you (farther from the mirror). Hold the objects such that they are both easily in the field of view.
If you had only to focus on the mirror itself, both would appear in focus simultaneously. However, I expect you will find that you can only focus on one object at a time (as long as they are sufficiently far).
Play around with it and (with one or both eyes), change focus back and forth between the reflections of the two objects. Tell us what you see!