Questions tagged [attenuation]
47 questions
13
votes
3 answers
Why does electromagnetism attenuate so much faster than gravity?
Electromagnetism and gravity are both inverse distance-squared laws, so why is gravity affected so much less by distance?
Is it that electrical charges tend to pretty much completely balance out beyond a micro scale?
Is it that matter interferes…
Jim Clay
- 537
9
votes
4 answers
Getting the spectrum of light source at high intensity (for low transmittance measurement)
I am trying to measure the transmittance spectrum through a liquid sample using a visible-NIR spectroscopy (a spectrometer connected to a fiber optics and a collimating lens at the end), with tungsten-halogen light source (through another…
smk
- 93
8
votes
1 answer
Why is sound attenuation greater in dry air than humid air?
I have just learned the surprising fact that the attenuation coefficient of sound in air depends strongly on relative humidity: at any given frequency, it can be several times larger in very dry air (10-20% RH) than in very humid air. The internet…
Ben51
- 10,037
3
votes
0 answers
How can we describe the attenuation of sound in an expanding gas cloud in a vacuum?
For example, suppose a spaceship explodes. The sound of the explosion will travel in the expanding cloud of escaping gas. I gather that it should rapidly weaken and the pitch should drop, but I'd like to get more specific than that. Are there any…
Logan J. Fisher
- 1,845
3
votes
3 answers
Why does audio signal amplitude always fall off at higher frequencies?
In the frequency spectrum of every real audio sample that I've ever seen, the amplitude of the frequency components is always higher at low frequencies, then rapidly falls off at higher frequencies.
For example, each of the following plots displays…
Jason C
- 1,034
3
votes
1 answer
Is it possible to take long-distance X-ray images at a high resolution in Earth's atmosphere?
It's my understanding that different wavelengths of EM radiation are affected by scattering and attenuation to varying degrees. Would a camera using only X-rays be able to take a picture of something (for instance) a few miles away with similar…
Twilitbeing
- 31
3
votes
3 answers
Are absorption and attenuation the same thing?
Are absorption and attenuation different words for the same thing? Wikipedia separate has articles on Absorption (Acoustics) and Accoustic Attenuation. I don't see a clear physical distinction between these two concepts, but I also don't know much…
WillG
- 3,770
3
votes
2 answers
What is the physical explanation for the attenuation of sound in Newtonian fluid?
My question refers to Stokes's law of sound attenuation in viscous medium. At this point I don't try to understand the mathematical form of the law - I simply don't understand how viscosity effects planar waves - this law states that planar waves…
user2554
- 547
2
votes
1 answer
The impact of electron density on photoelectric effect
I'm a second year radtion therapy student and i'm looking at the attentuation of KV energy beams. I'm wondering why for the photoelectric effect to occur does there need to be a high amount of 'inner'/ tightly bound electrons. Is it because this…
Tara Hellier
- 21
2
votes
2 answers
How does x-ray attenuation compare to sound wave attenuation?
When it comes to medical imaging (x-ray and ultrasound specifically) there seems to be a difference between the attenuation of sound and x-rays.
What I am gathering is as follows:
When it comes to x-rays, softer (lower frequency and thus energy)…
UnrulyTank
- 318
1
vote
0 answers
How to determine penetration depth of film using integral sphere setting UV-Vis data?
I am currently conducting research on polymer films and my current objective is to calculate the attenuation coefficient of the polymer film in order to determine its penetration depth.
Using an integrating sphere setup, I performed UV-Vis…
IK1024
- 11
1
vote
0 answers
Determining the photon beam intensity to confirm the placment of an object in a iradiated chamber
A parallel bundle of monoenergetic photons is used for imaging in the configuration below. The bundle passes through a layer of water with a thickness of 1 cm, then through a zone where a cube with a thickness of 1 mm is placed, and then through…
1
vote
1 answer
Beer's Law ultrasound attenuation, account for spherical spreading?
I've seen Beer's Law for narrow beam written as:
$$
I = I_0 \cdot e^{-\alpha x}
$$
${\alpha }$ - attenuation coefficient (depends on absorption and scattering),
$I_0$ - initial intensity,
$I$ - intensity after distance x
I want to also account for…
Carl Andren
- 13
1
vote
1 answer
How do you calculate light attenuation by wavelength at a given air mass coefficient?
I am trying to get a good view of light wavelength distribution as a function of viewing angle, with a specific interest as $z \approx 90^\circ$ near the horizon (sunrise/sunset). Air mass coefficient values by viewing angle are well known and…
KJ7LNW
- 163
- 6
1
vote
1 answer
What is the maximum distance that music is transmitted through the air?
I would like to hear your advice on which method to use to transmit music or speech in a frequency band that is sensitive to the human ear up to 3km. Everyone knows that the higher the frequency, the sharper the directivity, but instead, the…
Tiny
- 9