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# wavelengths on spectrum watch

1. I just want to know whether I have to memorise the wavelength values of all the waves on the spectrum and/or the wavelengths of each different colours. Hence such questions do come up where they ask to calculate the wavelength then asks to state what part of spectrum it belong or what colour it correspons? If i do have to remember is there a easy way since surely its not quite easy to remember all?
2. (Original post by Merdan)
(...) If i do have to remember is there a easy way since surely its not quite easy to remember all?
Do you want to know the colour of light at a certain wavelength? then you can use a 'board' on which all kinds of spetrums can be seen. I would recommend you to calculate the wavelength first and then you can analyse the colour of the light on the basis of the board next, if you are not sure which colour the wavelength has. I'm sure there are some good physics books which contains all kinds of colours and associated wavelengths

To be honest I don't know all colours of the wavelenghts, but I know that the violet colour begins about 400 nanometre and the red one about 630 nanometre. That is my guidance. When I have calculated the wavelength, I have an inuition what the colour could be. As a rule I look at my 'spectral board' to be sure.
3. I would recommend learning the colours as they can come up in questions quite frequently.

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4. I have had a task in which the colour of a wavelength was asked - I have used my physics book to answer the task. If you want to learn the colours nevertheless, I would recommend you to learn where the colours begins. Here is a list:

violett at 400 nm
blue at 450 nm
green at 490 nm
yellow at 560 nm
orange at 590 nm
red at 630 nm

It is enough to learn the 'beginnings', as all wavelengths which are between them have the associated color. 430 nm for instance is between 400 nm and 450 nm, so the colour must be violet.
5. (Original post by Kallisto)
I have had a task in which the colour of a wavelength was asked - I have used my physics book to answer the task. If you want to learn the colours nevertheless, I would recommend you to learn where the colours begins. Here is a list:

violett at 400 nm
blue at 450 nm
green at 490 nm
yellow at 560 nm
orange at 590 nm
red at 630 nm

It is enough to learn the 'beginnings', as all wavelengths which are between them have the associated color. 430 nm for instance is between 400 nm and 450 nm, so the colour must be violet.
Thank you abt that but what about the wavelength values of waves on electromagnetic spectrum. I couldn't find as clear values of those. Can you post the wavelengths where each electromagnetic waves begin?
6. (Original post by Merdan)
Thank you abt that but what about the wavelength values of waves on electromagnetic spectrum. I couldn't find as clear values of those. Can you post the wavelengths where each electromagnetic waves begin?
If I'm not mistaken the spectrum of the electromagnetic waves must be the same like the one of the light, as electromagnetism and the light have identical properties in terms of the wave.
7. (Original post by Kallisto)
If I'm not mistaken the spectrum of the electromagnetic waves must be the same like the one of the light, as electromagnetism and the light have identical properties in terms of the wave.
I thought that colour spectrum is specific to visible light part of the electromagnetic waves and there are other waves like gamma rays, microwaves... etc and I think each of them have specific wavelength range as well if im not mistaking.....
8. (Original post by Merdan)
I thought that colour spectrum is specific to visible light part of the electromagnetic waves and there are other waves like gamma rays, microwaves... etc and I think each of them have specific wavelength range as well if im not mistaking.....
I guess I have not understood your question clearly enough. I thought your questions refers to the visible spectrum, but I'm wrong. Here are the other wavelengths which are out of the visible spectrum:

radio waves begins at 10^6 m
micro waves begins at 10^-2 m
infrared radiation begins at 10^-4 m
optical waves (visible spectrum) at 10^-6 m
ultraviolet radiation begins at 10^-8 m
X-rays begins at 10^-10 m
gamma radiation begins at 10^-12 m.

Its quite easy to keep in mind, if you ask me.
9. (Original post by Merdan)
I just want to know whether I have to memorise the wavelength values of all the waves on the spectrum and/or the wavelengths of each different colours. Hence such questions do come up where they ask to calculate the wavelength then asks to state what part of spectrum it belong or what colour it correspons? If i do have to remember is there a easy way since surely its not quite easy to remember all?
You do need to have a rough idea what wavelengths correspond to what...

the visible spectrum is from about 400-700 nanometres with green in the middle (500-600 will usually do for A-level purposes.) if it is in the metres it is probably radio waves, millimetres is probably X-rays etc.

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