I read that a (sufficiently) white surface reflects more (visible) light than a mirror. Is that true? And if yes, why?

  • 2
    $\begingroup$ "A mirror" and "a white surface" are not opposites. You could argue that a mirror is also a white surface - just a white surface that happens to reflect specularly (parallel rays). $\endgroup$
    – Steeven
    Apr 16, 2021 at 10:09
  • $\begingroup$ Interesting perspective. $\endgroup$
    – Raffael
    Apr 16, 2021 at 10:13
  • 1
    $\begingroup$ To develop the first comment a bit more, you can consider the following thought experiment: Start with a mirror made of a homogeneous material, say stainless steel for instance, then break it into pieces again and again a couple of times, each fragment will reflect light as efficiently as the the initial mirror (albeit in a different direction). If you do this a large enough amount of time, you end up with a white powder, whose reflecting power is the same as the one of the initial mirror (only spread over a large amount of grains). $\endgroup$ Apr 16, 2021 at 12:30
  • $\begingroup$ Hi, please provide the reference which made that statement. It would be helpful to us, as then we could show what assumptions it made about a mirror's reflectivity $\endgroup$ Apr 16, 2021 at 14:06
  • $\begingroup$ Here’s one possible example: patentimages.storage.googleapis.com/c7/70/db/6a3db1bed0860d/… $\endgroup$ Apr 16, 2021 at 15:21

1 Answer 1


Have you ever wondered why things show colour? Well when light is incident on a surface, light of certain wavelengths are absorbed and we see the complement colours.For example a green surface absorbs light of all colours other than green. But a white surface is a surface that reflects out light of all wavelengths unlike a black surface which absorbs all light.

Now imagine shining a green laser at a mirror . What we get is a reflected green beam.if we repeat this experiment for all other 6 colours we will get similar results.So we can conclude that a mirror reflects light of all colours just like a white surface .

So what makes a mirror different from a white surface?

A mirror possesses specularity i.e parallel rays are reflected parallel to each other thus maintaining an image which does not happen for all white surfaces. A surface which is not a mirror does not reflect the parallel rays in a specular fashion so the reflected rays mix into one homogeneous white light without producing image.

So basically if I take a white surface and give it the property of specularity I get a mirror.

Typically how much light is reflected depends on the surface.For example if you take a sufficiently white surface it will reflect 100 % light but if you compare it with a household mirror that reflects only 80% light then the white surface would reflect more than the mirror.


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