Questions tagged [intensity]
The intensity tag has no usage guidance.
62 questions with no upvoted or accepted answers
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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 ...
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Difference between steady state intensity and saturation intensity in laser
Can someone explain the difference between steady state intensity and saturation intensity in lasers? And difference between gain at threshold and gain at steady state, why are these two gain equal?
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How does the intensity of light in a double slit experiment vary with the slit width?
I know this question has been asked quite a few times on the network but I still can't find a concrete answer. It's quite clear that intensity depends on the square of slit width in a single slit ...
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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 ...
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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 ...
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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 ...
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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 $...
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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 ...
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The relation between intensity and electric field
For a plane wave of the form $E=E_0 \cos(\omega t- k z)$, the intensity is $I=\frac{1}{2}c\epsilon_0E_0^2$. This can be derived by noting that $I=\langle S\rangle$, where $\langle
\,\rangle$ denotes ...
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Doubling up on Ear Protection NRR Equation
I'm planning to go to shooting ranges soon, and am looking for ear protection.
Let's say that I get an earmuff with a noise rating reduction (NRR) of $X\ \textrm{dB}$ and earplugs with $Y\ \textrm{dB}$...
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Why is the intensity of a beam of light the squared magnitude of the phasor and not just the squared magnitude of the real part?
I'm learning about phasors and light intensity and there are two conflicting things I've been told that I can't reconcile.
Firstly I've been told that a phasor $e^{-ikz+i\phi}$ is a mathematical way ...
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Calculating in-duct sound intensities from sound pressure measurements with mean mass flow
In the time domain and in free field condition the sound intensity can be calculated as $ \vec I(t)=p(t) \cdot \vec v(t)$ with $p(t)$ being the sound pressure and $\vec v(t)$ being the sound velocity. ...
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Why the intensity of a wave is $ \Psi \Psi^*$?
In here at the bottom, it says the intensity of a wave is the wave phasor times it's conjucate
$$ I(x) = \Psi \Psi^* = |\Psi |^2$$
But when I compute the intensity of an electromagnetic wave in c.g.s, ...
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Electric field/intensity for complex envelope
When calculating the propagation of a pulse I can either use an envelope-based or a carrier-based approach. For the carrier-based approach I can define my (focused) pulse with the central frequency $\...
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Solar panel voltage reducing by adding cellophane
For a physics report, I am aiming to answer the question How does the power output of a solar cell vary with the thickness of cling wrap laid over it?
I got a negative relationship between voltage and ...
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Spectral Radiation Intensity and Energy Density
I'm trying to prove the following relation
$$ I_{v} = \frac{c}{n} u_{v} $$
where $I_{v}$ is the (spectral) radiation intensity and $u_{v}$ is the respective energy density, $n$ is the refractive index ...
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Please help me formulate (and solve) a differential equation for a practical DIY problem concerning air sterilization (for covid)
Here I present the DIY air sterilisation project which this is about.
I want to calculate the overall sterilization rate of the device under some simplifying assumptions. (UVC is the hard ultra violet ...
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Calculate the amplitude and the frequency of the magnetic force acting on an electron
A free electron is located in the electromagnetic field of a laser with a given wavelength and intensity.
Is it possible to calculate the amplitude and frequency of the magnetic force that is acting ...
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Dependence of solar energy absorbed over a year on orientation of solar panel
I am trying to find how total solar energy incident, over a year, depends on the orientation of a tilted solar panel. The final goal is to find the optimum direction in which the panel should be ...
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Can high energy photons produce more photo current than a bit more intensity of photo electrons?
If we take 2 case :
Case 1: Very high energy photons and a bit less intensity
Case 2: less energy photons but a bit high of intensity
In both case ,both energy of photons are greater than the ...
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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 ...
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Sound Relationships
Whats the relationship between amplitude, volume, and wave energy. I have tried many websites but none have helped me yet and I believe maybe someone on here can help me.
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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 ...
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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 ...
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Intensity Poynting
Take a plane wave propagating in the $\hat{z}$ direction in a non-magnetic linear dielectric. The real electric field is then given by
$$\vec{E}(r,t) = E_0\, e^{-k_i z}\cos(k_R - \omega t)\, \hat{x} ...
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How to Calculate the Spectral Intensity per Solid Angle in a Tungsten Bulb - Photodetector Setup
I have a setup with a tungsten bulb. The bulb has a 2cm diameter aperture in front of it. When the bulb is turned on, light from it hits a bi-convex lens 21.5cm away which then focuses the light onto ...
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Sunlight intensity, temperature and lens flare
1- How can I calculate the sunlight intensity in percentage? (without external influences such as clouds or pollution).
In this site SunCalc, Solar constant changes from location to site or from time ...
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Modeling an Electrolyzer System
In this study, the authors provide an equation for operating cell voltage: $V_{cell} = V_{rev} + V_{act} + V_{ohm}$, the sum of the reversible overvoltage, the activation overvoltage and the ohmic ...
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How HBT interferometery works?
I am still confused about how HBT interferometry for star angular size works after reading about it on the internet and in papers. Mathematics usually does not help before I do not catch the way the ...
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Does intensity of sound depend on temperature or humidity?
The intensity of sound $I$ can be written as $$ I = 2 \rho v (af \pi)^2$$
I googled and found that increase or decrease of temperature doesn't have any impact on sound intensity. But why is that? ...
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Intensity of light and energy at a photonic level
If I understand correctly, the intensity of light is proportional to the number of photons hitting a certain area.
If we then look at a single photon when described as a transverse wave, is its own ...
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Can we say that amplitude of light scattered by air molecules is inversely proportional to the square of wavelength of incident light?
As per Rayleigh's criteria of scattering of light by air molecules the intensity of scattered light is inversely proportional to the forth power of wavelength.
AND WE ALSO SAY :
Intensity of a wave ...
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Effect of thickening polariser on intensity pattern
I've performed an experiment where microwaves were sent through a polariser of varying thickness, composed of $11$ slits (width and spacing both $6$ mm).
To vary the thickness of the polariser, this ...
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Why would there be a larger data dispersion at minimums than at maximums in a graph of intensity against path difference?
I'm doing a rather simple experiment concerning the superposition of two waves and the impact that path difference of 2 identical waves has on recorded intensity at that point. However, there is ...
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Why a wave whose intensity is modulated sinusoidally have different frequency compared to original wave even though intensity depends on amplitude?
While experimenting to find the velocity of light, instead of finding the velocity of light, we used the light wave whose intensity was varied sinusoidally and found the velocity of light using the ...
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Acceleration due to incident radiation on plate
I have tried the following question and getting a wrong answer.
Monochromatic light of intensity I falls over a blackened plate of area A, at an angle $\theta$ as shown in the figure. If 70% of light ...
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How does the spot size of light change the photocurrent?
I want to understand the photo electric effect. If I shine light at a surface then a photon can knock an electron off the surface if its energy $h\nu$ is larger than some minimum material specific ...
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Sound, additive principle or not? How to prove?
If we have $N$ sound sources with $L_1, L_2,...$ with intensities $I_1, I_2,...$. How to prove that
$I_{total}= I_1 + I_2 + ... $ but $L_{total}$ is NOT $L_1 + L_2 + ... $
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Is there a way to calculate the intensity of light absorbed that passed through a solid?
So I have lab I need to do for school and I need a formula that calculates the intensity of light transmitted through a solid (in my case sheets of paper). I had a probe that measured the intensity of ...
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How is energy in terms of Intensity and Amplitude comparable to Energy in terms of Frequency?
Let's take LASER light. It has a high energy ,in terms of Amplitude, let's take a red light, of same frequency ,we are giving each of these to two atoms , now atom no $1$ is subjected to LASER light ,...
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Unequal arm length Michelson Interferometer Light Intensity
Imagine a Michelson interferometer with unequal arm length. A laser beam with an electric field of the form $$E(t,z) = 2E\cos(ωt+kz)$$ is incident on a 50/50 beam-splitter. The first arm is of length <...
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Electron emission and photoelectric effect affected by intensity
It is said that when visible light is directed onto a metal surface, it doesn't emit electrons from the surface because intensity doesn't affect it. However, then it is said (relating to the equation) ...
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Poynting vector and intensity of a signal
Given a plane monochromatic electromagnetic wave propagating in $x$ direction, with associated electric and magnetic fields of the form:
$\overrightarrow{E}(x,t)=\overrightarrow{E_0}\cos(kx-\omega t), ...
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Double-slit diffraction: Reduction of intensities
In a double-slit experiment, why do the intensities of the interference maxima decrease with the increasing diffraction angle?
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Changes to an EM-wave that is propagating in an inflating space
I am trying to get an easier picture of what happens to an em-wave considering space expansion. My question is: If a star in a non-inflating space emits light recorded at a certain distance of the ...
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Complex intensity in electric field (transfer matrix)
Currently I'm coding a transfer matrix approach in C#. Hence, I come up with certain electric fields $E$. At each position I have a propagating field to the right $E_{\text{right}}$ and one to the ...
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Photoelectric Effect Graph: Interpretation of Intensity vs
After performing dimensional analysis of the current versus voltage graph when studying the photoelectric effect, this graph should measure units of siemens. It shows, however, high intensity and low ...
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Variation of Intensity when a source moves
When a sound source moves, frequency perceived by the observer is changed due to the doppler shift. Does this apply to intensity too? If yes then how.
Thanks!
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Will non-radially radiating sound plane wave propagate forever without losing intensity?(assuming no dissipative forces)
I have encountered on a textbook that established the relationship that intensity is proportional to the square of displacement amplitude and the square of angular frequency. However, the equation ...
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How to calculate the intensity profile of a pulsed laser beam given its pulse energy?
I am trying to calculate the intensity profile of a pulsed laser given that the intensity envelope is Gaussian. I also know the full width half maximum and pulse energy of the pulse.
What are the ...
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