Why Water is Colorless: The Science Behind a Clear Liquid | Kinooze

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Discussion Overview

The discussion revolves around the reasons why water is perceived as colorless, exploring various explanations related to light absorption and reflection. Participants also touch upon the properties of color and light reflection in different materials, particularly focusing on the behavior of white and colored objects in relation to infrared light.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants argue that water should appear black if it absorbs all colors, while others contend that it is colorless because it allows visible light to pass through without significant absorption.
  • There is a suggestion that water reflects light outside the visible spectrum, contributing to its perceived colorlessness.
  • Some participants note that purified water can have a slight blue tint, challenging the idea that water is entirely colorless.
  • Discussion includes the reflection properties of white objects, with some asserting that white reflects infrared light better than darker colors, while others caution against generalizing this based solely on visible light interactions.
  • Participants debate whether a red object reflects infrared light as effectively as a white object, with differing opinions on the specifics of color reflection.

Areas of Agreement / Disagreement

Participants express disagreement on the explanations for why water is colorless, with multiple competing views presented. The discussion on the reflection of infrared light also remains unresolved, with differing opinions on the properties of colored versus white objects.

Contextual Notes

Some claims depend on specific definitions of color and light interaction, and there are unresolved aspects regarding the absorption and reflection of infrared light by different materials.

gracy
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Here is the link which explains this.But i don't think it is right because according to the explanation given water should be black not colourless.http://kinooze.com/2012/09/09/why-is-water-colourless/I think water reflects light which is not in our visible range,right?
 
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gracy said:
And what about reflection?color of object all depends on reflection,so water reflects..?
Water is transparent.

Water can have a colour, or rather a slight tint, but I don't want to go into the details. Look at other threads in PF, such as https://www.physicsforums.com/threads/why-water-blue.133850/
 
DrClaude said:
This is the worse explanation I have ever seen. Water is colourless because it let's visible light pass through, without absorbing much.

Exactly !

its is noted that purified (distilled) water will have a slight blue tint to it

that last statement on the linked page is just so wrong ...
In case of water, almost all the colours are absorbed. No colour is reflected back, thus no colour reaches our eyes. That is how water appears to be without any colour.

if all the colours were absorbed then yes, it would be black

Dave
 
davenn said:
Exactly !

its is noted that purified (distilled) water will have a slight blue tint to it

that last statement on the linked page is just so wrong ...if all the colours were absorbed then yes, it would be black

Dave
Ok can you please tell me if white color reflects infrared light also?
 
What your eye sees as white is a combination of light of wavelengths across the spectrum.
 
IT does to a better degree than say black

feel the difference in temperature between a white and a black painted car that is in the sun
 
davenn said:
IT does to a better degree than say black

feel the difference in temperature between a white and a black painted car that is in the sun
So the object which is reflecting most nearly all of the wavelength of visible spectrum (i.e white color object)will reflect infrared light also.right?
 
  • #10
gracy said:
Ok can you please tell me if white color reflects infrared light also?
First, infrared is a big part of the electromagnetic spectrum, so there is not a single thing as infrared light. As davenn said, in general withe things will also show greater reflection of IR radiation, especially in the near IR. But you could, at least in principle, have a material that is white but still absorbs all IR radiation.
 
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  • #11
great response :)
 
  • #12
DrClaude said:
First, infrared is a big part of the electromagnetic spectrum, so there is not a single thing as infrared light. As davenn said, in general withe things will also show greater reflection of IR radiation, especially in the near IR. But you could, at least in principle, have a material that is white but still absorbs all IR radiation.
But white color object would reflect IR better than any other colored object say red or blue,is it right?
 
  • #13
davenn said:
IT does to a better degree than say black

feel the difference in temperature between a white and a black painted car that is in the sun

You cannot say this a priori. The color of an object is (mainly) based on its interaction with light in the visible range.

The main part of the Sun's light is in the visible spectrum, which black absorbs and thus becomes warmer. You cannot draw a conclusion about the IR properties solely based on this, you would need a source mainly active in the IR spectrum.
 
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  • #14
gracy said:
But white color object would reflect IR better than any other colored object say red or blue,is it right?
If its blue, probably, but if it is red, absolutely not! It is already reflecting in the red part of the spectrum, so it is probably also reflecting in the near IR.
 
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  • #15
Orodruin said:
You cannot draw a conclusion about the IR properties solely based on this,

True and I didn't :)

DrClaude expanded on the theme well :)

DrClaude said:
First, infrared is a big part of the electromagnetic spectrum, so there is not a single thing as infrared light. As davenn said, in general withe things will also show greater reflection of IR radiation, especially in the near IR. But you could, at least in principle, have a material that is white but still absorbs all IR radiation.
 
  • #16
  • #17
davenn said:
True and I didn't :)

DrClaude expanded on the theme well :)

If you ask him to feel a black and white car in the Sun, this seems to imply that this is an argument for white reflecting more of the IR. It is an argument for white reflecting more visible light.

I agree DrClaude wrote it nicely.
 
  • #20
gracy said:
Okyou mean red color object reflects red color better than white color .
No, this is not true. White is reflecting all colours, including red.

A red object is as likely to reflect infrared frequencies as a white object. It's all in the specifics of the pigment.
 

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