Spoon Optics-Virtual Inverted image with a concave mirror

**ilzmaster** · Feb14-10, 05:13 PM

When you look at a spoon, like at a mirror, the image of yourself appears to be on the other side of the mirror/spoon, where light does not go! So the image must be virtual!

So tell me, since a concave mirror must produce a real inverted image when you are far from the focal point http://en.wikipedia.org/wiki/Real_image how does a spoon produce a virtual inverted image?
OR is it that it only appears to be virtual and is really real? Which is problematic since you definitely see yourself on the other side of the spoon, just like with a plane mirror.

p.s. conceptual answers are preferred. I have been able to find values with the thin lens/mirror equation which work (f=-3, s=-4, s'=-12) but cannot ray trace anything like it or comprehend it. Criticisms on my f,s, and s' numbers are welcome too (and yes i know a negative s is weird but still, it works).

Thanks to anyone who dares answer!

**Doc Al** · Feb14-10, 05:39 PM

Originally Posted by ilzmaster

When you look at a spoon, like at a mirror, the image of yourself appears to be on the other side of the mirror/spoon, where light does not go! So the image must be virtual!

Why do you think the image appears to be on the other side of the spoon? The surface is curved, so how can you tell?

I'm looking into a spoon right now. Looks like the usual inverted real image to me, on this side of the spoon (in the bowl, not behind it).

Try pointing a pencil at the spoon and look at its image.

For a ray diagram, look here: Concave Mirror Image

**ilzmaster** · Feb14-10, 06:44 PM

I am at a college campus so I haven't used metal spoons for months.
I just got ahold of one. It is amazing. You're right, the image is real and not behind the spoon. The pencil tip helped too.

Thank you Doc Al!