Questions tagged [intensity]

The tag has no usage guidance.

23 questions with no upvoted or accepted answers
Filter by
Sorted by
Tagged with
2
votes
0answers
49 views

Are / Why are the H II regions positively charged?

One of the questions in our recent astrophysics course homework was to find the general opacity $\kappa$ of H II regions. We know that the H II regions are almost entirely ionized hydrogen and I ...
2
votes
0answers
219 views

What does the Interferogram of a FTIR-spectrometer show ? Is it instantenous intensity vs time or time averaged intensity vs time?

I try to get a clear understanding of FTIR spectroscopy and it is unclear to me what exactly the interferogram shows. I know that we see the intensity of the superpositioned beams where we vary the ...
2
votes
1answer
169 views

What determines how much power goes into each diffraction order?

Imagine a grating with infinite number of slits, and the spacing D between slits is larger than the wavelength so that there are high order diffractions. In each of the diffraction directions the ...
2
votes
0answers
97 views

Does the intensity of LED lights decrease after turning on?

LED lights come on immediately the power is supplied. This is different to the older compact fluorescent-tube lights. I am always impressed by the brightness of the LED lights when they come on. Later ...
1
vote
0answers
50 views

Electric Field Intensity

The electric field intensity everywhere is $E=E_0-j$ (y-direction) in vacuum (say $E_0=5$). if you have an infinite-perfect conductor starting at the $x \geq 4$ plane and $x < 4$ is vacuum. What ...
1
vote
0answers
17 views

Is this the correct interpretation of specific intensity?

I've always been taught to define specific intensity as the following quantity: if I have a detector here next to me with an area element $dA$ and I detect a power element $dP$ from a source of solid ...
1
vote
0answers
51 views

Photoelectric effect - the reason for exponential graphs and a misconception about the concept of intensity

We have this basic PASCO Photoelectric Effect equipment in our lab and there are two things I would like to ask about the experiment. We keep either the area apertures or wavelength filters fixed and ...
1
vote
0answers
41 views

Derivation of scattering coefficient as a function of number density of scatterers

I'm trying to derive the usual formula for intensity of light passing through scattering medium: $$I=I_0\exp(-\alpha x),$$ where $\alpha$ is the scattering coefficient (assuming it's constant), and $...
1
vote
0answers
40 views

Quadratic relationship between amount of light and intensity

In a spectroscopy experiment, we were able to control the amount of light shining onto a sample by adjusting two small slits. By investigating the relationship between slit width and the intensity of ...
1
vote
0answers
64 views

Light wavelengths and intensity at 10 m depth in coastal water

I’m planning an experiment in tanks under controlled conditions in which we’ll collect marine animals and observe their behaviours. We want to replicate to the best the light that they receive under ...
0
votes
0answers
7 views

Calculating intensity from Debye formula for Iron

Following is the question I am trying to answer: and this is what I have done so far: Any idea how I can progress from here? I think plotting a graph of intensity against |K| or 2*theta is the way ...
0
votes
0answers
17 views

Gain Coefficient of lasers and intensity paradox?

It can easily be shown that the intensity of a laser is $$I = I_0e^{z\gamma} \,, \tag{1}$$ where $\gamma$ is the gain coefficient. It can also be shown that $$\gamma = \frac{\gamma_0}{1+I/I_{\text{...
0
votes
1answer
24 views

Luminostiy, Flux, Intensity definitions and meaning

I am taking astrophysics course and we are constantly talking about Luminosity,Brightness,Intensity,Flux etc. I thought that I understand the idea properly but I see now that I dont. Intensity is the ...
0
votes
1answer
108 views

What is the relation between Reflectance and Intensity?

I am just reviewing Fresnel's equations where Reflectance $R$ is equal to $$R=|r|^2$$ where $r$ is the complex reflection coefficient. Is there an equation that relates $R$ to intensity or is there ...
0
votes
0answers
30 views

“Intensity” as a unified term

I am seriously having trouble with the word “intensity”. Does it have different meanings when it is placed next to another word (light intensity for example) or does it always mean the same (power/...
0
votes
0answers
22 views

How much information can be yanked out of an XRD Graph?

I have an XRD Graph(plotted data peaks between 2theta and intensity).I already Know the d-value corresponding to each peak.The material has an orthorhombic symmetry.What more information can I ...
0
votes
0answers
116 views

How is radiance conserved? - Power/intensity misconception

Before getting to the main question I'd like to clear some pretty basic concepts regarding energy/power/intensity as my physics is pretty rusty. According to wiki In radiometry, radiant flux or ...
0
votes
1answer
27 views

Fourier Transforms and bell frequency example

I am stuck on the following question: I can do the part a rather easily, but the part b i am stuck on. For now I have shown that I(Wo) = 1/(2piK^2) and 1% of this is 1/(200PiK^2) I have also ...
0
votes
1answer
183 views

How to use Malus's law to get real output energy from a polarizer

As we know, the Malus's law is: $I=I_0\cos^2\theta$ Presently, I have a polarizer system (one half wave plate in front of a polarizer) in the lab, and have a powermeter. So, I can get two key ...
0
votes
1answer
32 views

How do we calculate the irradience of an EM wave?

I've been told that the Irradience = time average of the electric field squared. However, I've also been told that it's equal to the total Amplitude of the electric field squared. I'm kinda confused ...
0
votes
1answer
48 views

Is there a math formula to calculate difference of dB of sound, in different pure transmitting mediums?

Is there a math formula to calculate the difference of dB of sound, in different pure transmitting mediums? For example, based on a measurable decibel level, with a known frequency, a known atomic ...
-1
votes
1answer
88 views

Wave optics, intensity distribution

Do Gaussian beams have a gaussian intensity distribution? If so, why? Does the intensity distribution depend on the profile of the light beam?
-1
votes
1answer
38 views

Photon energy and power

My question has to do with the solar spectrum. I understand sunlight is composed of light of different wavelegnths, and these wavelegnths have different energies associated with them. I also ...