Nested arrays of grazing incidence mirrors allow astronomers to focus radiation.

Nested  array  of  grazing  incidence  mirrors  allow  astronomers   to  focus  X-ray  radiation.  The astronomer  x-ray  deal  with  the  study  of  x-ray observation  and   detection  from  astronomical  object.The x-ray   detectors and  Telescopes   are  taken  to  high altitude or  into  space  by  balloons.

Capacitance is the ratio of the change in electric charge of a system, to the corresponding change in its electric potential. There are two closely related notions of capacitance: self capacitance and mutual capacitance. Any object that can be electrically charged exhibits self capacitance. A material with a large self capacitance holds more electric charge at a given voltage than one with low capacitance. The notion of mutual capacitance is particularly important for understanding the operations of the capacitor, one of the three elementary linear electronic components (along with resistors and inductors).

Explanation: