1) market failure, 2) the tragedy of the commons, and 3) the underprovisioning of public goods. One of the first principles of free markets is that for them to work effec- tively, the full costs of an activity must be borne by the involved parties.
A reflector telescope uses two mirrors instead of two lenses. <span>A </span>refracting telescope<span> works bending light through a lens so that it forms an image. </span>
