Calculating Multiple Images in a Plane Mirror

• vu95112
In summary, the conversation is about a person trying to find the distances from themselves to the first three images seen in two plane mirrors. The first image is 10 ft behind the left mirror and the second and third images are 30 ft and 40 ft, respectively. A diagram can be helpful in understanding the concept.
vu95112
Plane Mirror
A person walks into a room that has, on opposite walls, two plane mirrors producing multiple images. Find the distances from the person to the first three images seen in the left-hand mirror when the person is 5ft from the mirror on the left wall and 10 ft from the mirror on the right wall.

I know the first image is 10 ft because in the plane mirror, the image is as far behind the mirror as the object is in front. I don’t know how to figure out the second and the third images? I need you help please. Thank you.

Vu95112

Try making a diagram like that found in scrolling down the page at http://dev.physicslab.org/Document.aspx?doctype=3&filename=GeometricOptics_PlaneMirrors.xml":

It may help to keep you from getting confused. The first image in the left mirror is the virtual image of the person and as you say 10' behind the mirror. Apply the same logic to the first image in the right mirror. It would be 5' behind the mirror and since the mirrors are 15' apart, would seem to be 20' away. And so forth.

Last edited by a moderator:
Hello denverdoc,
Thank you very much for your help. A diagram is very useful.
The first image is 10ft
The second image is 30 ft
The third image is 40 ft

Thank you,

Vu95112

What is a plane mirror?

A plane mirror is a flat, smooth surface that reflects light rays in a regular pattern. It is also known as a flat mirror or a perfect mirror.

How does a plane mirror work?

A plane mirror follows the law of reflection, which states that the angle of incidence (incoming light ray) is equal to the angle of reflection (outgoing light ray). This means that the reflected image in a plane mirror will appear to be the same distance behind the mirror as the object is in front of the mirror.

What are the characteristics of a plane mirror?

The characteristics of a plane mirror include: it reflects light rays in a regular pattern, the reflected image appears to be the same size as the object, the image is virtual (cannot be touched), the image is laterally inverted (left and right are switched), and the image is upright (not inverted).

What is the difference between a plane mirror and a curved mirror?

The main difference between a plane mirror and a curved mirror is the shape of their surface. A plane mirror has a flat surface, while a curved mirror has a curved surface. This results in different properties, such as the size and type of image formed.

What are some applications of plane mirrors?

Plane mirrors have many practical applications, including in household mirrors, car mirrors, telescopes, and periscopes. They are also used in physics experiments and optical illusions. Additionally, plane mirrors are used in laser technology, such as in laser printers and barcode scanners.

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