MCAT physics (Light and Geometrical Optics)

[DiamondBar]

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1. What are exactly are "images" formed by concave and convex mirrors? I do not understand what they mean/represent in the real world. At the point labeled "image" formed by rays, does the image "appear" to be at that point IN the mirror?? or does it mean that the image "appears" to be there in some sort of apparition?

2. Please also explain Real vs Virtual image using real life examples?

3. Why can concave mirrors create real and virtual images while convex mirrorrs can only create virtual images?

 

[tartrate]

1 & 2.

A real image means there are actual light rays hitting that point, so it will be received by an object placed in that position, for example a screen or piece of paper (light shining through film in a theater produces a real image). A virtual image is kind of an illusion, with no image actually present at the perceived position. The image is extrapolated from light that has been bent in a certain way to give an impression of the image. When looking at a flat mirror, it appears as if light rays are coming out from behind the mirror, which is not the case. This is an example of a virtual image, since really, it's the light reflecting off the mirror that's giving the illusion, not someone in your wall.

3.

It's a useful exercise you can do for yourself to really understand the concept of images. Try drawing ray diagrams for each mirror, and consider their trajectories after being reflected. Do they meet at a single point, or do they scatter in different directions? If they scatter, can you extrapolate a perceived "origin" or source of light they may be scattering from?

 

[BerkReviewTeach]

2. Please also explain Real vs Virtual image using real life examples?

Virtual: "Objects appear closer than they really are" is printed on your side mirrors. These mirrors produce a virtual image of the cars behind you that all fit on your mirror. Those small virtual images you see while looking forward are of things behind you.

Real: A projector connected to a computer owned by a professor giving a gawdawful powerpoint presentation on microvilae sends a beam of light that is really on the screen you are looking at. A real image can be projected onto a surface.

 

[phltz]

Also, a real image can be seen (from certain angles) floating in space, like a hologram. A virtual image appears to be behind the mirror or lens in question, a real image in front.