Lab 2 - Spectra Lab Final 2.10.20.pdf - Emission...

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Emission Spectroscopy, Wien’s Law, and Doppler Shift Lab Objectives Learn the basic mechanism behind what produces an emission spectrum and how they allow us to identify ionized gasses Learn about the excited states of hydrogen and how to apply the photon energy equation to identify the wavelengths of the photons emitted during energy level transitions Understand how Wien’s Law can be used to approximate the surface temperatures of stars Understand how the Doppler effect can be used with absorption spectra of stars to measure their radial velocity Equipment Calculator A printed copy of this lab A Ruler Background Information Astronomy is one of the few sciences where you simply can’t just grab a sample of what you are studying and experiment with it. Most of the objects you are studying are too far away and it would take lifetimes to retain a sample or even send a to probe them to gather data. Luckily, the light astronomical objects give off carries tons of information about them. In this lab, we will explore some of the valuable information that can be extracted from the light of celestial objects. This will be done primarily by doing the simple analysis of spectra through the topics of emission spectroscopy, Wein s Law, and Doppler Shift. This lab assumes you have already completed Module 5 and are already familiar with these topics. However, the high points of each topic that are needed to have success in this lab are reviewed in the following sections. Spectroscopy Spectroscopy is the study of how light interacts with matter. You might not realize it, but in some way, it effects your everyday life. The interaction of light and matter is what makes your lawn appear green or the sidewalk next to it feel hot. In astronomy, it can be used to tell us the same things about stars -- what color they are as well as their temperature. We’ll talk more about temperature later but the most fascinating thing about how light interacts with matter is that it can be used to reveal its sources composition. This is because the unique elements that something is made of react in a specific way to light. Atoms have something we call energy levels or energy states. Atoms always want to find themselves in the lowest possible energy state which we refer to as the ground state. If an atom is not in the ground state, then we say that it is in excited state. An atom may have many different excited states, but its goal will always be to go back to the ground state. In order to do this, energy needs to be released and this is done in the form of photons, or particles of light. We refer to this as an energy transition and an atom might go through several energy transitions before it returns to its ground state. Since each element has different energy levels with different energy transitions that are unique to it, the photons that are released are also unique. What this all really boils down to is that the light something gives off carries

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