Investors Careers. Life Science Cameras. Control Software. Physical Science Cameras. OEM Portfolio. Support Service and Support. Learning Centre Asset. What is Light Emission Light can be produced by matter which is in an excited state and, as we will show, excitation can come from a variety of sources.
Black body radiation A body at a given temperature also emits a characteristic spectrum of light called black body radiation. Different colors of light are associated with different photon energies.
Essentially, a photon is a packet of light. For example, a photon of red light would have less energy than a photon of blue light. This ties in with wavelengths because red has longer wavelengths than blue which results in less energy. Electrons only exist in shells, the area around a nucleus.
Specific energy levels correspond to specific shells. In an atom, the amount of energy levels that are allowed depend on the structure of protons and electrons. Emission is the process of elements releasing different photons of color as their atoms return to their lower energy levels.
Atoms emit light when they are heated or excited at high energy levels. The color of light that is emitted by an atom depends on how much energy the electron releases as it moves down different energy levels. When the electrons return to lower energy levels, they release extra energy and that can be in the form of light causing the emission of light.
On the other hand, absorbed light is light that isn't seen. The energy of the photon will determine the color of the Hydrogen Spectra seen. The hydrogen atom is a single electron atom. It has one electron attached to the nucleus. The energy in a hydrogen atom depends on the energy of the electron. When the electron changes levels, it decreases energy and the atom emits photons. The line emission and absorption spectra of atoms can indeed be calculated from first principles, but with the sole exception of hydrogen this cannot be done analytically, and it requires some substantial number-crunching to figure out.
Basically, it requires you to discretize a certain differential operator into a big matrix, and then to diagonalize that matrix. Atomic line emission and absorption spectra come from the differences between the discrete energy levels in the atom, and those are the solutions of a complex dynamical problem in quantum mechanics, involving all of the interactions between the electrons and the nucleus as well as each other. Typically, calculating the emission spectrum of hydrogen is within the reach of a 'mature' course in quantum theory in an undergraduate degree often the second QM course within the degree , but the tools for even an approximate calculation of atomic spectra for multi-electronic atoms require a further, dedicated course on atomic physics.
Your guess of "electrons jumping between energy levels" is definitely on the right track in fact, it's basically the answer to your question! Electrons fly around the nucleus in something called orbitals these are not exactly the same thing as orbits , but for the sake of this explanation the difference doesn't really matter. Any given orbital has a specific energy associated with it see note below. For example, in the case of hydrogen, the ground state orbital has an energy of Now, under normal conditions, an electron spontaneously tries to minimize its energy, and it does so by jumping to an orbital with a lower energy.
However, that energy cannot just vanish conservation of energy, right? If you make the calculation, you'll see that such a photon has a wavelength of roughly nm - deep into the UV region of the spectrum. Of course, this is just an example of a possible transition: we could equally have considered a jump from the second excited state to the ground state, or from the third excited state to the first excited state.
In many cases, these other transitions occur in the visible part of the spectrum. In fact, each atom has a series of spectral lines associated with it each spectral line coming from a different transition between a couple of orbitals , and these are so unique that they are often thought of as a "fingerprint" of the atom. Note on orbital energies : the precise value for the energy of an orbital depends on a number of different factors, and to calculate them you need the full "machinery" of quantum mechanics.
It is not true that hydrogen would only emit red light. There are many different wavelengths at which hydrogen can emit light - even ultraviolet which is more energetic radiations than blue light. It could be in another energy level. You must have studied about the Lyman, Balmer, Paschen series. The radiation comes when those transitions occur between a higher energy level to a lower energy level. So, the electrons does not have to do any "effort". If you were doing this as an experiment, you would have heated the hydrogen gas first and recorded its line spectra.
Of course, that energy it obtains should depend on the heating given to the gas in the first place. There are multiple energy levels in all atoms that electrons can occupy so there are many possible colours even for the simplest single atoms. First things first: atoms emit light when electrons in a higher energy orbital drop to a lower energy orbital.
The energy of the emitted photon matches the energy lost by the electron and that energy determines the colour blue is higher energy than red, UV even higher than blue and so on.
Orbitals describe the possible places around the atom where an electron can be and different ones have both different shapes and different energies.
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