You must Sign In to post a response.
  • Why do black surfaces reflect less light and absorb more light?

    Why do black surfaces reflect less light and absorb more light?
  • Answers

    4 Answers found.
  • Black surfaces have greater absorptivity, and hence, they absorb most of the light falling on it. Black surfaces act as blackbodies for almost all wavelengths of light.
    I cannot tell exactly why it is so.

  • Before any explanation, we should know that there are three primary colours viz., red, blue and green. All these three colours combine to form white and absence of these form black colour. This same theory applies to surfaces or light of various colours.

    Any body or surface appears of a particular color because it reflects light of that wavelength. For example leaves appear green because the pigment chlorophyll present in it reflects green wavelength of light and absorbs the rest of the wavelength.

    Similarly If a body appears white it means it is not absorbing any of the light and reflects all the incident wavelengths.Since white light is a combination of all wavelengths of light.

    A black body or surface in a similar manner absorbs all the wave lengths of lights incident on it and reflects none. So the absence of any wavelength in the reflected light make it appear black.

  • Hey there,
    I dont think any of the above answers or apt as per the concepts of physics."BLACK" It has very less wavelength. This can be reasoned out by following explanation.

    There is no colour So called "BLACK"

    * BLACK is nothing but the combined reflection of"VIBGYOR".That is VIOLET+INDICO+GREEN+YELLOW+ORANGE.

    * Since the wavelength is very less The frequency(inversly proportional to it) is more.

    *As frequency is high (as per the laws of dispersion the high frequency colour will be dispersed more)the black is dispersed

    *The conclusion is any Black surface acts as an Conductor of all coloured light and rather reflecting it, it will retain within itself (as Heat energy).

  • The answer by pooja is simple and coherent but the above answer is confusing. The coombined reflection of all the colours is white but not black.
    Coming to the question in proper, I think the questioner wants to know why the particular surfaces have greater absorptivity.

    The correct answer for this can be explained by the concepts of atomic physics. The light energy of particular wavelength absorbed by particular object is used for the transition of electrons from the orbits of lessr energy (inner orbits) to the orbits of higher energy (outer orbits). The light energy of particular wavelength emitted is due to the transition of electrons from the orbits of higher energy to lower energy which is actually responsible for the colour of the object.

    Conclusion: The characteristic colour of the object is due to electronic transitions which inturn depends on the electronic configuration and nuclear configuration.

    'Complacency kills the progress,strive for the best..'
    'Share to grow, Grow to share'

    Ask expert section

  • Sign In to post your comments