Prism Spectrum Questions

Hi,

When light passes thru a prism, the red color should bent
less and violet more. But how come when I look thru a
prism on the lower half of the right with the light
entering the lower half of the left (as the usual setup
is). I can see the violet appearing on top and red on
the bottom of the spectrum staring directly at the
prism. Since red should bent less. Shouldn't I see the
red on top rather than violet??

Thanks.

Kyle

Kyle wrote:
Hi,

When light passes thru a prism, the red color should bent
less and violet more. But how come when I look thru a
prism on the lower half of the right with the light
entering the lower half of the left (as the usual setup
is). I can see the violet appearing on top and red on
the bottom of the spectrum staring directly at the
prism. Since red should bent less. Shouldn't I see the
red on top rather than violet??

Are you sure it's a *single* prism you are looking through?

Oftentimes in amateur astronomy, double amici direct vision prisms are
used, and these reverse the directions of the output rays.

See
http://users.forthnet.gr/ath/jgal/sp...ope/amici.html

Thanks.

Kyle
--
I. N. Galidakis
http://users.forthnet.gr/ath/jgal/
------------------------------------------
Eventually, _everything_ is understandable

"Ioannis" wrote in message
news:1109771589.55649@athnrd02...
Kyle wrote:
Hi,

When light passes thru a prism, the red color should bent
less and violet more. But how come when I look thru a
prism on the lower half of the right with the light
entering the lower half of the left (as the usual setup
is). I can see the violet appearing on top and red on
the bottom of the spectrum staring directly at the
prism. Since red should bent less. Shouldn't I see the
red on top rather than violet??

Are you sure it's a *single* prism you are looking through?

Oftentimes in amateur astronomy, double amici direct vision prisms are
used, and these reverse the directions of the output rays.

See
http://users.forthnet.gr/ath/jgal/sp...ope/amici.html

Thanks.

Kyle
--
I. N. Galidakis
http://users.forthnet.gr/ath/jgal/
------------------------------------------
Eventually, _everything_ is understandable
I suspect this may be the demonstration of the 'eye inversion'. If you
create a ray of light, and it is shone at the top of your eye, you see the
light as being at the bottom of the field of view. What is happening, is
that the image in your eye, is actually inverted (the image is formed with
the 'top', at the bottom of the retina), and the 'software' in your brain,
inverts this.

Best Wishes

"Kyle" wrote in message
oups.com...
Hi,

When light passes thru a prism, the red color should bent
less and violet more. But how come when I look thru a
prism on the lower half of the right with the light
entering the lower half of the left (as the usual setup
is). I can see the violet appearing on top and red on
the bottom of the spectrum staring directly at the
prism. Since red should bent less. Shouldn't I see the
red on top rather than violet??

Thanks.

Kyle

The eye perceives the relative positions of the different colors based on
the angles of the incoming light rays. Violet is bent more, so appears to
come from a position higher up, while red is bent less, and appears to
originate from a low position.

Johannes