[alancalverd (OP)]

Isaac Newton analysed white light with a glass prism that he bought in Cambridge market, and thus established spectroscopy and the wave model of light.

If anyone else had ever bought a prism, wouldn't they have noticed how it analyses white light?

If nobody else had ever noticed it, why was anyone selling prisms in a market?

[Bored chemist]

Newton's actual, clever, discovery was that, with the same sort of prism, you can recombine the light and make white again.

Prior to that there was no understanding of how a prism worked.
It was believed that it "added" colour to the light, rather than finding the colours that were already there.

https://www.nextgurukul.in/wiki/concept/kerala/class-10/physics/part-2_colours-of-light/dispersion-and-recombination-of-white-light/3958923

[alancalverd (OP)]

Sir Isaac Newton was the first to use a glass prism to obtain the spectrum of sunlight. Newton split the colours of the spectrum of white light further by using another similar prism. But he could not get any more colours. He then placed a second identical prism in an inverted position with respect to the first prism, as shown in the following Figure.

Oh dear. So white light is composed of line spectra?

[Bored chemist]

Oh dear. So white light is composed of line spectra?

You seem to have hallucinated that comment.

[alancalverd (OP)]

No, it's the logical consequence of the statement I highlighted in blue. If you can't get any more colors by adding a second prism, there must be a finite number of distinct colors, i.e. a line spectrum, not a continuum.

[Bored chemist]

there must be a finite number of distinct colors

Seven of them.
Robert of York gave battle in vain.
Were you not aware of this?

[alancalverd (OP)]

If green is 530 nm and yellow is 590 nm, are you telling me that there is no component of white light with a wavelength of 560 nm?

And the failed soldier was Richard, Duke of York, nor Robert.

[Bored chemist]

If green is 530 nm and yellow is 590 nm, are you telling me that there is no component of white light with a wavelength of 560 nm?

Of course not.
That would be silly. I never said anything like that; it's just that hallucination of yours again.

Have you ever looked at the sun's spectrum a-la- Newton?
No slit, no lenses?
There's a good chance that the  green 530 nm and yellow is 590 nm would overlap with 560nm.
.

[alancalverd (OP)]

To put it more simply, what name would you give to an electromagnetic wave train centered on 560 nm with, say, 15 nm bandwidth, given that "green" and "yellow" are already assigned elsewhere?

[Bored chemist]

given that "green" and "yellow" are already assigned elsewhere?

Are they?

What name would you give to a poodle given that "Dog" is assigned to an Alsatian?

[paul cotter]

The visible spectrum of the sun is largely continuous, apart from some dark absorption lines.

[Bored chemist]

The visible spectrum of the sun is largely continuous, apart from some dark absorption lines.

As noted by Wollaston in 1802 and thus not known to Newton in 1666
Fraunhofer made a study of them and they are usually named after him.

I wonder if Alan has got to grips with the fact that you need more than just a prism to get narrow enough bandwidths for his questions to be relevant.
Perhaps he would like to tell us what "new" colours you can get by using a second prism.
Octarine? Infragreen and ultrayellow maybe?

The point remains that Newton's really clever bit wasn't splitting light into colours but recombining the colours to make white.
He initially did it with a prism but the idea is still demonstrated in primary schools today.
https://en.wikipedia.org/wiki/Newton_disc