Phy107 Essay Example | Topics and Well Written Essays - 750 words

Phy107 - Essay Example A blackbody emits infrared wavelengths at room temperature. As the temperature increases, the blackbody starts to emit visible light, starting from red to orange, yellow to white and blue with increasing temperature. When the blackbody turns white, it is already emitting ultraviolet radiation. Stefan's Law states that the total energy radiated by a blackbody per unit surface area is directly proportional to the fourth power of its absolute temperature. This means that as temperature increases, the wavelength of the radiation emitted decreases. Doppler Effect, or Doppler shift, happens when an observer is moving relative to the wave source - there is a change in the frequency of the wave perceived by the observer. This means that when we are approaching the wave source, we perceive a higher frequency. When we are receding from the wave source, we perceive a lower frequency. Spectroscopy refers to the dispersion of an object's light into its component colors. By analyzing the light emitted by an object, the physical properties of that object such as temperature, mass, luminosity and composition can be inferred by an astronomer. Continuous spectrum, as opposed to discrete spectrum, refers to energy at all wavelengths. It is emitted by warm objects. The spectrum of light with missing frequencies is called absorption spectrum. ... Continuous spectrum, as opposed to discrete spectrum, refers to energy at all wavelengths. It is emitted by warm objects. The spectrum of light with missing frequencies is called absorption spectrum. The missing frequencies correspond to wavelengths of light that were absorbed. 3. Explain how a beam of light passing through a diffuse cloud may give rise to both absorption and emission spectra. Suppose that a beam of light passes through a gas, some of the frequencies of the light will be absorbed by the gas. The rest of the frequencies will be able to pass through. When these surviving frequencies are dispersed through a prism, they will show a spectrum with gaps on it. The visible spectrum will correspond to the emission spectrum while the dark bands will correspond to the absorption spectrum. 4. List three properties of a star that can be determined from observations of its spectrum. a. Total energy that the star radiates b. Luminosity c. Surface temperature CHAPTER 5 1. List three advantages of reflecting telescopes over refractors. a. Refractors tend to be heavier overall than reflecting telescopes because of their longer solid tubes and require a larger housing and a more massive mount. b. Reflectors don't disperse color as most refractors are to one degree or another. c. In a refractor the lens can only be supported along the edge so that the path is clear for light to come through unobstructed. 2. How does Earth's atmosphere affect what is seen through an optical telescope The Earth's atmosphere is constantly moving, and different layers bend the light from a star in different directions, blurring our view from the ground. 3. What are the advantages of a CCD over a photograph The major advantages of CCD-based cameras are