What Are Emission and Absorption in Physics?

In summary: If you heat the vapours of some substances, the vapour emits light of characteristic colour/s, the exact colour being determined by the arrangement of the electrons in the atoms of the particular elements in that substance. This emitted light is the emission spectrum, and you can see it in things such as neon lights, or coloured fireworks, or school science lab experiments, and even your kitchen gas stove.An alternative arrangement is to shine white light through the gaseous state of a substance, and use precison optical instruments to examine the light that passes through. You will find some of the individual colours that were in the white light have gone missing, or are at least reduced, because they have been absorbed by the atoms in the
  • #1
J-Girl
38
0
emission and absorption?? confused!

hiii, I am just wondering if anybody can give me a very simple definition of each of the two terms, and what the main difference is. Is emission when a wave enters a denser medium (from air to water)? and absorption when a wave enters a medium of lower refractive index number?- just a guess lol, but anyways, would really appreciate some input!:)
 
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  • #2


Are you talking about emission and absorption spectra?
 
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sorry i should have specified, yes emission and absorption spectra. not stated clearly in my book and I am spose to learn this! i just can't find a good definition on the internet
 
  • #4


A google search will turn up more explanations, and better ones, than you'll get on PF.

But I'll give a brief explanation to get you going. If you heat the vapours of some substances, the vapour emits light of characteristic colour/s, the exact colour being determined by the arrangement of the electrons in the atoms of the particular elements in that substance. This emitted light is the emission spectrum, and you can see it in things such as neon lights, or coloured fireworks, or school science lab experiments, and even your kitchen gas stove.

An alternative arrangement is to shine white light through the gaseous state of a substance, and use precison optical instruments to examine the light that passes through. You will find some of the individual colours that were in the white light have gone missing, or are at least reduced, because they have been absorbed by the atoms in the vapour. This is the absorption spectra. You need something better than an untrained naked eye to see this effect. Again, the colours that go missing are characteristic of the elements in that vapour.

To excite a substance to the point that it glows and emits light, it is sprayed into a gas flame.
 
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  • #5


Yeah, if you're talking about spectra.
Emission sprectra is when something hot glows in it own characteristic spectrum.
Absorption is when something cold absorbs (ideally white) light in its own characteristic spectrum.
 
  • #6


DaveC426913 said:
Absorption is when something cold absorbs (ideally white) light
Yes, that's a good point. A gas, but not heated, not necessarily, anyway. I'll amend what I wrote.
 

FAQ: What Are Emission and Absorption in Physics?

What is the difference between emission and absorption?

Emission is the process in which energy is released in the form of electromagnetic radiation, while absorption is the process in which energy is absorbed by atoms or molecules, causing them to move to higher energy levels. Essentially, emission and absorption are opposite processes.

How do emission and absorption relate to light?

When an atom or molecule absorbs energy, it can transition to a higher energy state. This energy is then released through emission, typically in the form of light. The specific wavelengths of light emitted or absorbed depend on the energy levels of the atom or molecule.

Why are emission and absorption important in astronomy?

Emission and absorption play a crucial role in understanding the properties of celestial objects. By analyzing the specific wavelengths of light emitted or absorbed by these objects, scientists can determine their temperature, composition, and other characteristics.

How does the emission and absorption of greenhouse gases affect the Earth's climate?

The Earth's atmosphere contains greenhouse gases such as carbon dioxide, water vapor, and methane, which absorb and emit infrared radiation. This traps heat in the atmosphere and leads to the greenhouse effect, contributing to the Earth's overall temperature and climate.

What are some examples of emission and absorption in everyday life?

Emission and absorption are present in many everyday phenomena. For example, the glowing of a light bulb is a result of emission from heated filaments, while the colors we see in objects are due to selective absorption of certain wavelengths of light. In addition, the colors of fireworks are produced by emission from different chemical compounds, and the absorption of UV rays by sunscreen protects our skin from harmful radiation.

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