Optics question: Looking at mirrors from parallel to the surface

• Grasshopper
Also, for very oblique incidence, you could be seeing images from multiple reflections from the two glass faces. That can seriously distort what you see if you are looking at a small bright object.

Grasshopper

Gold Member
I did a little experiment recently where I took a plane mirror and held it underneath a ceiling light. Then, I began to lower my head so that my view was closer and closer to the surface. When I did this, the image of the light began to drift lower and lower in the mirror until it completely disappeared.

I am curious about what would happen if I repeated the experiment using a convex mirror (by this I mean curved TOWARD the ceiling light). Because we can see the reflection of the sun on the ocean, I imagine that the image wouldn't fall below as much if I were to place my head near the surface of the mirror.

Unfortunately, most physics websites I've seen describe curved versus plane mirrors from the perspective of far away from the surface of the mirror. They'll usually only focus on light coming perpendicular from the object and how that reflects on the mirror.

So can anyone help me find some good diagrams about what these types of mirrors look like according to a viewer near the surface? Any contributions you can give are appreciated.

Was the mirror silvered on the front of the glass or the back of the glass?

anorlunda said:
Was the mirror silvered on the front of the glass or the back of the glass?
It’s hard to tell, but I THINK it’s silvered on the front of the glass (the flat mirror I used; and again, when my eyes were further away from the mirror, I could see the ceiling light, but when my face was right at the surface, the reflection was well below what I could see).

Grasshopper said:
I am curious about what would happen if I repeated the experiment using a convex mirror (by this I mean curved TOWARD the ceiling light).
You can use a big spoon to test that. Or a metal bowl.

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sophiecentaur
You may have seen an object floating on a still lake. This shows the inverted image, which touches the feet of the object without a gap. If the surface is curved in a convex manner, the image is smaller.

anorlunda said:
Was the mirror silvered on the front of the glass or the back of the glass?

Grasshopper said:
It’s hard to tell, but I THINK it’s silvered on the front of the glass (the flat mirror I used; and again, when my eyes were further away from the mirror, I could see the ceiling light, but when my face was right at the surface, the reflection was well below what I could see).
It's unusual to find a normal domestic mirror that's silvered on the surface. Surface silvering is very easily damaged. Some stainless steel mirrors are used where ruggedness is needed. Or was this 'lab equipment'?
If there is a surface layer of glass (say 6mm thick) then you could expect some refraction effects when the paths are well away from the Normal (very oblique). Also, for very oblique incidence, you could be seeing images from multiple reflections from the two glass faces. That can seriously distort what you see if you are looking at a small bright object. (A laser pointer will show these up well).

We'd really need some sort of a diagram of your setup or we could have a different picture in our heads. If you google search for ray diagram mirror reflection ( or some variation on that) and select Images, you will see many different hits. You could copy a suitable image - that suits your question best.

sophiecentaur said:
If there is a surface layer of glass (say 6mm thick) then you could expect some refraction effects when the paths are well away from the Normal (very oblique).
Just touch a pencil to it and see the gap to the reflection. If it is not very clean you can see the reflection of every speck of toothpaste, or whatever.

sophiecentaur

1. How does the angle of incidence affect the angle of reflection when looking at a mirror from a parallel angle?

The angle of incidence, which is the angle between the incident ray and the normal (a line perpendicular to the surface of the mirror), is equal to the angle of reflection when looking at a mirror from a parallel angle. This is known as the law of reflection, and it applies to all types of mirrors, including flat, curved, and spherical mirrors.

2. Why do objects appear reversed when looking at a mirror from a parallel angle?

When looking at a mirror from a parallel angle, the light rays reflecting off the mirror's surface create an image of the object. The image appears reversed because the light rays follow the law of reflection, meaning they bounce off the mirror at the same angle that they hit the mirror. This causes the image to appear flipped horizontally.

3. Can you see your own reflection when looking at a mirror from a parallel angle?

Yes, you can see your own reflection when looking at a mirror from a parallel angle. This is because the light rays from your face hit the mirror at the same angle that they reflect off, creating an image of yourself in the mirror.

4. How does the distance between an object and a mirror affect the image when looking at a mirror from a parallel angle?

The distance between an object and a mirror does not affect the image when looking at a mirror from a parallel angle. The image will always appear to be the same size and distance from the mirror as the object, regardless of the distance between the two.

5. Are there any practical applications of understanding optics when looking at mirrors from a parallel angle?

Understanding optics when looking at mirrors from a parallel angle has many practical applications, such as in the design of mirrors for telescopes, microscopes, and other optical instruments. It also plays a crucial role in industries such as automotive and aerospace, where precise reflections and images are necessary for safety and functionality.