MadSci Network: Physics

Re: When you put a spoon into water, what is it called?

Date: Mon Mar 20 02:41:47 2000
Posted By: Matthew B. Weyerich, Technical Coordinator,ES&R Dept., CPI Corp.
Area of science: Physics
ID: 952544070.Ph

Hi there, Beth!

Really sorry to take so long getting this to you! My computer is having 
trouble talking to other computers these days, so I don't always know if my 
answer gets through. I keep trying, so, assuming this one does…

I think what you are referring to is called "refraction". That's a funny 
word for light rays getting "bent" because they don't travel at the same 
speed in water, glass, etc., as they do in empty space.

If light travels from a vacuum to another medium it gets "slowed down" by 
electromagnetic interactions. The air-water mix we live in (not too dense, 
so, still pretty much like a vacuum,) scatters and slows the light. Then, 
however, the light hits a more dense thing, like clear glass. This slows it 
down some compared to the rest of the light which doesn't hit the glass. We 
mostly don't notice this. But…

When light goes from air, into glass, into water, through some more glass, 
then out into the air again, finally striking our retinas, well, we notice 
something odd!

Look at your glass of water with the spoon in it from the top. What do you 

The handle of the spoon looks bent! Is it, really?

No. What you're seeing is a "trick" called refraction. The light hitting 
the spoon, then your eye, is different from the light which has to hit the 
water, the spoon, more water, then your eye! 

Another person asked me a similar question once. "Fishing" for the answer, 
I decided to have a little fun. (Hope you do, too.)  Here is a link to my 
answer: a previous answer

I'm going to make a guess about the magnification you ask about. I THINK 
the spoon looks bigger under the water (inside the glass) for the same 
reason I mentioned above. (Refraction.) 

(I THOUGHT I could prove this by plopping a spoon into a nifty clear wine 
glass full of water. I THOUGHT I'd see different magnification as I rotated 
the glass...knowing about refraction, as I do. Shows what I know! It all 
looks the same to me! That spoon really does look bigger, doesn't it?!)

I still think my original response to your answer holds true, though.

You see, refraction is what makes lenses work. My glasses are lenses. So 
are magnifying "glasses".

Our spoons are magnified by "lenses" made of water, glass, and air. 
Refraction is what makes the lenses work! (It's not really an illusion. 
It's really about how light REALLY works!)

If you want to get really technical, you can research "refraction", "index 
of refraction", or, "Snell's Law" on your computer. (If you need a place to 
start, check out the MadSci Search Engine.)

I hope this helps, Beth, and I hope you receive it! E-mail me if I can help 
you more.
Your MadSci,

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