A radial or circular balance
I think its excitement but i'm not fully sure
Explanation: However, to work efficiently, one side of the mirror requires twice the amount of light that the other side is receiving. In this way, the darkened side can see through the brightly-lit side but not vice-versa. This is also a reason because of which the glass is called one way glass.
One-way mirrors are coated with a half-silvered layer,allowing the mirror to reflect half the light that strikes its surface. ... The name half-silvered comes from the fact that the reflective molecules coat the glass so sparsely that only about half the molecules needed to make the glass an opaque mirror are applied.
