What colour is a mirror?
The colour of an object is dictated by the wavelengths of light that are reflected off the object's surface atoms. So, what does a mirror reflect back?
Asked by: Kate Watts, by email
In white light, which includes the wavelengths of the visible spectrum, the colour of an object is dictated by those wavelengths of light that its surface atoms fail to mop up. As a perfect mirror reflects back all the colours comprising white light, it’s also white.
That said, real mirrors aren’t perfect, and their surface atoms give any reflection a very slight green tinge, as the atoms in the glass reflect back green light more strongly than any other colour.
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Robert is a science writer and visiting professor of science at Aston University.