A department store is a establishment offering a wide range of in different areas of the store under one roof, each area ("department") specializing in a product category. In modern major cities, department stores emerged in the mid-19th century, reshaping shopping habits and the definition of service and luxury. Similar developments were under way in (with ), in () an.
[pdf] In a spectrometer, such a discrete spectrum appears as a series of colored lines. A particular set of lines or wavelengths is characteristic of a certain element and can be used as a “fingerprint” for identifying an. In 1913 Neils Bohr proposed a physical model to describe the spectrum of the hydrogen atom. It was the birth of Quantum Mechanics! As a consequence, the energy of the electron around the nucleus is also quantized! In a real life experiment we can never measure the energy of the electron. The emission spectrum of atomic hydrogen has been divided into a number of spectral series, with wavelengths given by the Rydberg formula. All other (neutral) atoms contain more electrons and are therefore many-body systems requiring. With a spectrometer, the emitted light can be broken down into its various colors or wavelength components and its “spectrum” is observed.
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