Fill in the blanks.(1) consists of electric and magnetic disturbances, or waves, that travel through space. Human eyes see one form of this energy, called (2) . All forms of electromagnetic radiation, including X-rays and radio waves, make up the (3) . Each type of radiation can be classified in two ways. (4) measures the distance between the peaks on a wave and (5) is the number of waves that occurs each second. Scientists study radiation with (6) , which collect and focus light. The (7) the opening that gathers light in a telescope, the more light that can be collected. A(n) (8) uses lenses to bring light to a focus, and a(n) (9) uses mirrors to do the same thing. The process of linking several telescopes together so that they can act as one is called (10) .

The light that we see and can not see is actually Electromagnetic radiation. It consists of various rays like X-rays, gamma, radio, IR etc. Out of the complete EM spectrum we can only see 7% i.e. the visible part of the spectrum. These waves are categorized basis their wavelength and frequency. Telescopes are used to study the EM spectrum. Bigger the opening of the telescope more light can be gathered and the image will be brighter and better. In refractor telescopes, convex lenses are used to collect the light while Reflector telescopes use concave mirrors are used to gather the light. When multiple telescopes, mirror segments are used in sync to work as one, the arrangement is called as Astronomical Interferometer.