← Light rays and plane mirrors

Plane-mirror image characteristics

Haldis stands 2 m in front of the mirror in a dance studio. Her image seems to stand inside the wall, 2 m behind the glass. The wall is solid, and nothing is in there.

You know the screen test. This lesson states what a flat mirror's image is like: four facts you can use without drawing anything.

A perfectly flat mirror is called a plane mirror.

Haldis stands 2 m in front of the plane mirror, and her image stands 2 m behind it.

mirrorHaldisher image2 m2 m
As far behind as in front: 2 m in front puts the image 2 m behind.

A plane mirror's image is always as far behind the mirror as the object is in front.

The image is not on the glass: it sits behind the mirror, at that equal distance.

The image is upright: Haldis's head is up, and so is her image's.

The image is the same size as the object.

mirrorlampits image1.3 m1.3 m1.2 m1.2 m
Upright and the same size, at the matched distance: the lamp's image, 1.2 m behind.

The image is virtual: a screen placed where it seems to stand would catch nothing.

So the full profile reads: virtual, upright, the same size as the object, and as far behind the mirror as the object is in front.
A plane mirror's imagethe image isvirtualuprightthe same size as the objectas far behind the mirror as the object is in front
The four-part profile in one list.

A floor lamp stands 1.2 m in front of a plane mirror on a closet door. Where is the lamp's image, and is it upright?

The image is as far behind the mirror as the lamp is in front.

The lamp is 1.2 m in front, so the image is 1.2 m behind the mirror.

A plane mirror's image is upright.

The image is 1.2 m behind the mirror, and it is upright.

Greer's little brother is 1 m tall. How tall is his image in the hallway's plane mirror?

A plane mirror's image is the same size as the object.

He is 1 m tall, so his image is 1 m tall.

His image is 1 m tall.

A cat sits 1.4 m in front of a plane mirror. Enter the distance, in m, from the mirror to the cat's image behind it.

Elowen stands 3 m from her bedroom's plane mirror. She says her image is upright and the same size as she is. Is Elowen correct?

Fintan says: 'Your image in a plane mirror sits right on the glass, like a photo printed on the mirror.' Is Fintan correct?

Your turn

Which set of words describes the image a plane mirror makes of a person standing in front of it?

A dog stands 0.6 m in front of a plane mirror. Enter the distance, in m, between the mirror and the dog's image.

Greer looks at a vase's image in a plane mirror. The vase stands 0.8 m in front of the mirror. Where is the image?