Course Hero Logo

Mirrors focus light by reflecting light rays from its

Course Hero uses AI to attempt to automatically extract content from documents to surface to you and others so you can study better, e.g., in search results, to enrich docs, and more. This preview shows page 1 - 2 out of 2 pages.

Mirrors focus light by reflecting light rays from its curved surface.All of the light incident on the lens or mirrorconverges onto the focal plane, where an image of the field-of-view is formed.The distance between the lens or mirror and the focal plane is known as the focal length. Reflectivemirrors can be made physically larger, because they are supported across their entire back surface, unlike refractors.Reflecting telescopes are more mechanically stable.Lensespossess the unfortunate property of refracting various wavelengths of light to slightly different focal plan. For reflectors, a variety of designs are used to permit the focused light
beam to exit the telescope:Prime focus – located inside the tube, where the focused light rays convergeNewtonian focus – a small, flat mirror, set at an angle, directs the lightout through the side of the telescope.Cassegrain focus – a small, curved secondary mirror is emplaced at the top of the tube, directing the focused light out through a hole cut inthe center of the primary mirror. This is the most common design, and is used by the Hubble Space Telescope.Full coverage of the electromagnetic spectrum is essential forunderstanding the cosmos because:Many celestial objects & phenomena emit radiation only in non-optical parts of the spectrum.Some regions of space are opaque tovisible light, but allow other wavelengths to pass through. The radiation or energy emitted by objects is termed a spectrum. This radiation can be emitted at many wavelengths orfrequencies at the same time.The spectra of celestial objects can be: 1. Continuous – Energy is emitted over a range of wavelengths (frequencies) without gaps 2.Pure emission –Energy is emitted only at a number of very specific wavelengths with large dark gaps between the emission lines. 3.Continuous with absorption – Energy is emitted over a range ofwavelengths with occasional dips and gaps.Continuous with emission and absorption – Energy is emitted over a large range of wavelengths with occasional dips, gaps and peaks.For an object emitting radiation as a blackbody, the wavelength of peak emission is inversely proportional to temperature, a relationship known as Wien’s law. As the temperatureincreases, the peak wavelength decreases - the peak moves towards bluer wavelengths. Wien's Law is can be stated as follows, where wavelength is measured in nanometers andthe temperature is expressed in Kelvin. Wien's Law: λmax = 3 x 106 / TempThe surface temperature of celestial objects can be determined by measuring an object’s spectrum andfinding the peak value of emitted light.Emission: Matter can release energy, which it previously absorbed or generated internally, by emitting photons. On the atomic level,electrons drop from high to low energy levels, emitting radiation. When an object is heated, energy is transferred to it, that energy is subsequently released as the object attempts
End of preview. Want to read all 2 pages?

Upload your study docs or become a

Course Hero member to access this document

Term
Summer
Professor
N/A
Tags
Astronomy, Photon, Light, Wavelength, Electromagnetic spectrum

Newly uploaded documents

Show More

Newly uploaded documents

Show More

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture

  • Left Quote Icon

    Student Picture