Why Black Absorbs Light And White Reflects Light?

How many of you have wondered why black absorbs light and white reflects light? Actually, that isn’t how it works.

Black doesn’t absorb light. In reality, what absorbs all the wavelengths of light (abbreviated as VIBGYOR) appears black (I suppose you got what I meant). Also, black is not a colour. Black is the absence of colour.

Similarly, white doesn’t reflect light. What reflects light is white in colour and the reflection of all wavelengths of light makes an object appear white.

Consider this fact. If you take a black object and subject it to a certain wavelength of light except visible light, it would appear white! So, an important conclusion here is that an object appears black only if it absorbs “visible light” [light between the wavelengths 4 x 10 -7 m (violet) to 7 x 10-7 (red)] and appears white if it reflects visible light.

Now, we come to the other topic of discussion- How can something absorb or reflect light? Whenever light falls on any object, the object only absorbs the light if it possesses energy equal to the difference of the energies in two successive shells of an atom (ΔE). If it is more or less, the light will either be reflected or transmitted through the object.

In absorption, the light energy is converted to heat energy (That is why a black object heats up when exposed to light) and in reflection, light is bounced back from the object when the atoms in it vibrate.

However, there is one more case. Light can be transmitted through the substance.The atoms absorb the light energy for a very short duration of time and then release it to the neighbouring atom. I have already talked about this in my article “How Light Passes Through Glass?”.

So, how was it? Feel free to comment in the Comments section.

Author: Venkata Bhamidipati

Source Of Picture: https://www.photovideoedu.com/Learn/Articles/the-color-of-light.aspx

2 thoughts on “Why Black Absorbs Light And White Reflects Light?

  1. Hi
    I liked it but one question
    My elders use to say not to wear black in summer and when we sit under sunlight wearing a black dress it “burns”(burning sensation)
    Why that so?

    Like

    1. Hello. Please continue to support my blog.
      The phenomenon you talked about also occurs due to a substance absorbing light. Along with light, heat too is absorbed by a substance. So, we can say that an object which absorbs more heat appears black and which doesn’t absorb much heat appears white.
      When you sit under the Sun wearing a black dress, it tends to absorb both the light and heat. That’s why you get that burning sensation.

      Like

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