Why can't the focus of a plane mirror be virtual like in a concave mirror?

In summary, the focal point of a plane mirror is considered to be at infinity because the reflected rays do not intersect. However, this is a paradoxical use of the term "infinity" and the focal point could potentially be located behind the mirror.
  • #1
Sam Morse
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I read somewhere that the focus of a plane mirror is at infinity because rays after reflection from a plane mirror don't intersect anywhere. But why can't the focus be virtual as in case of concave mirror ?
 
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  • #2
Sam Morse said:
I read somewhere that the focus of a plane mirror is at infinity because rays after reflection from a plane mirror don't intersect anywhere. But why can't the focus be virtual as in case of concave mirror ?

When considering where the focal point is we use two parallel rays of light incident on the mirror, how will these two rays be reflected from a plane mirror?
 
  • #3
Sam Morse said:
I read somewhere that the focus of a plane mirror is at infinity because rays after reflection from a plane mirror don't intersect anywhere. But why can't the focus be virtual as in case of concave mirror ?
The two parallell rays of light we use to determine the focal distance will still be parallell and with the same distance from each other at infinity.
Saying that the focal point is present at infinity is a nonsense paradox of the terminology infinity just as my above explanation. The focal point could likely be behind the mirror, saying that the two parallell rays would be separated infinitly from each other at infinity in front of the mirror.
 

What is the focus of a plane mirror?

The focus of a plane mirror is a theoretical point located behind the mirror at the same distance as the object in front of it. It is the point where all reflected rays appear to intersect.

Is the focus of a plane mirror the same as the focal point of a convex or concave mirror?

No, the focus of a plane mirror is a virtual point, whereas the focal point of a convex or concave mirror is a real point where parallel rays converge or diverge after reflection.

How is the focus of a plane mirror determined?

The focus of a plane mirror is determined by drawing a line perpendicular to the mirror's surface at the point where the object is located. The focus is then located at the same distance behind the mirror as the object is in front of it.

What is the significance of the focus of a plane mirror?

The focus of a plane mirror is important in understanding the principles of reflection and image formation. It helps to explain why objects appear to be the same size in a mirror as they are in reality, and why images in a mirror appear to be reversed horizontally.

Can the focus of a plane mirror be physically located?

No, the focus of a plane mirror is a virtual point and cannot be physically located. It only exists in the mind's eye as a point where reflected rays appear to intersect.

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