Intensity Definition and 898 Threads

In the book Introduction to Quantum Optics: From the Semi-classical Approach to Quantized Light by Grynberg, Aspect and Fabre I came across the following statement on page 385: "By the end of the nineteenth century, classical electromagnetism,..., provided a wave description of almost all...

Hi all, I am trying figure out this diffraction problem. I have to find the intensity distribution of a four slit fraunhofer diffraction grating using the convolution theorem. I can do the math and all...but I do not know how to start it! The only information I am given is the slits have...

Hi there, im doing school project regarding Solar Food Dehydrator. Can tell me what is the formula to calculate the light intensity from the sunlight?

I'm trying to figure out the intensity of light in different sections of a 2d airy disk from a point source, but I'm not sure how to calculate it. Does anyone have any good sources?

Homework Statement Show that the exit intensity as a function of Io (intensity out of light source) and θ12 (angle of second polarizer compared to the first polarizer) is I = (Io/8) sin(2(θ12)))^2 Homework Equations Malus' Law I = Io (cosθ)^2 The Attempt at a Solution I1 =...

Homework Statement A plane monochromatic electromagnetic wave with wavelength λ = 2.2 cm, propagates through a vacuum. Its magnetic field is described by \vec{B} = (Bx\vec{i} + By\vec{j})cos(kz+ωt) where Bx = 1.8E-6 T and By = 3.8E-6 T, and i-hat and j-hat are the unit vectors in the +x and...

Homework Statement A bird watcher is hoping to add a particular song bird to the list of species she has seen. If a person, only 2.35 m from the bird, hears the sound with an intensity of 1.9 10-6 W/m2, how far could the bird watcher be from the bird and still hear it? Assume no reflections or...

I have a 100watt xenon lamp , the UV component comprises of 5-6% of the total spectrum emitted by the xenon lamp . How do I calculate at what power is the UV light emitted ? Is the whole spectrum being emitted at 100 W or is the power distributed through the spectrum? How is this...

Homework Statement In a double slits experiment, the intensity at the central fringe is I. What will be the intensity at the central fringe when each slit is widened 2 times? Homework Equations The Attempt at a Solution My suggestion is that the intensity will be 2I...

Hi all, I was just looking for some assistance in reconciling the equivalence principle and the varying intensity of the gravitational field. (I'm in high school so go easy on me, I'm just studying Einstein's Relativity for the general reader). For convenience let's keep with Einstein's example...

I am taking AS level Physics rite now, and wanted to know what exactly determines the energy of a wave. Well since I have recently learn of stationary waves(sound waves) being standing. I know that they are formed by the superimposition of the reflected waves on the incident waves. This causes...

Homework Statement A tiny vibrating source sends waves uniformly in all directions. An area of 3.25 cm2 on a sphere of radius 2.50 m centered on the source receives energy at a rate of 4.20 J/s. (a) What is the intensity of the waves at 2.50 m from the source and at 10.0 m from the source...

Homework Statement If the intensity level at distance d of one trombone is 70 dB, what is the intensity level of 76 identical trombones, all at distance d? Homework Equations β = (10 dB) log10(I/I0) I0= 1.0 x 10-12 W/m2 I = power/area The Attempt at a Solution 70db = 10db log10(I/I0)...

Two speakers A and B are separated by 1 meter, the point P is 4 m away from speaker B. If P is a person for what frequency does he hear that the intensity have a minimum?. (The listener hear that the sound intensity reduces and increases).I don't know the distance from P to B. (They form a...

Two speakers A and B are separated by 1 meter, the point P is 4 m away from speaker B. If P is a person for what frequency does he hear that the intensity have a minimum?. (The listener hear that the sound intensity reduces and increases).I don't know the distance from P to B. (They form a...

When a point source emits sound, the sound travels away from the source as a series of wavefronts - all being spherical shells - away from the source right? Now, we say the energy is conserved if we neglect damping forces in the medium, and so the power delivered by the source should be...

Homework Statement Electric charge of density ρℓ = 5 μC/m is distributed along the arc r = 2 cm, 0 ≤ ∅ ≤ ∏/4, z = 0. Find the electric field intensity at (0, 0, z) Homework Equations dE=(dQ(r)/(4∏ε(r^2))) (unit vector R)The Attempt at a Solution Letting pL be the charge density, letting r^2 =...

I have a 150 W Xenon lamp with me and I need to know what is the intensity(W/m^2) of light being radiated on a surface at x distance away . How do I do it ? Can I use a photodiode, if yes then how ?

Thank you for the help!

I'm doing a solar cell characterization project. But due to some fault in my solar simulator(I'm getting different results from another set up), I'm now figuring a way to check the intensity of light shone by my simulator on cell. I'm trying to obtain it from the corrected data of my cell (Isc...

The site http://physics.nist.gov/PhysRefData/Handbook/Tables/hydrogentable3.htm shows the intensity of various photon energy values from hydrogen. I was not able to see how this intensity was observed (ie. was it from a specific experiment, or does one simply look at the sun and count photons...

Homework Statement A jackhammer with a sound power of 10 W is operating in the countryside. Calculate the intensity levels at distances of 2.0 m and 50.0 m from the jackhammer. Calculate the corresponding levels in dB. Homework Equations β = (10dB) log (I/Io) where, β = sound...

hi could somebody explain to me how organ pipes work? so far, i figured out that there are standing waves in an organ pipe, that are determined by the length and the question of whether there is a closed or open end. but what determines the intensity between these possible frequences(e.g...

A sound is measured to have a decibel level of 30dB. If the intensity is decreased by a factor of 2 by how much does the intensity level change? β=10 x log(I/Io) β=Intensity level I=intensity of the object Io= Threshold of hearing(human) If the I increase so the β increase If so the...

Hey there! I'm doing some experimental work at a microscope, where the lamp in use is stated to be "Lamp bulb: 12 V DC, 100 W halogen lamp bulb (Osram HLX 64623 or Phillips 7724)." I'm doing some calculations to analyse some of my images, and in there I need the intensity distribution of...

Homework Statement Two identical flat capacitors with no dielectric material inside are connected in series to a voltage source. The electric field intensity inside the capacitors is E. If the space inside one of the capacitors is filled with a dielectric material of ε=9 how strongly did the...

A student typing in a computer cluster generates a sound level of 55 dB. What will the dB level the night before essays are due when there are 30 equally noisy students working in the cluster? dBo = 55 Ihearing = 1E-12 W/m2 Bo = 10log(I/Ihearing) 55 = 10log(I/Ihearing) 55 =...

Homework Statement You are standing in between two sets of railroad tracks. On one set of tracks a train is initially 200 m away and approaching you with a constant speed of v0 = 11 m/s. On the other set of tracks second train is at the same distance and moving away from you at the same...

The central maxima is of highest intensity and then the successive maximas keep reducing in intensity. Has it got something to do with increasing number of waves which sort of interefere (the word has not been used in the sense of intereference pattern but as a normal english word) with the...

Homework Statement Laser light of wavelength 632.8 nm falls normally on a slit that is 0.0210 mm wide. The transmitted light is viewed on a distant screen where the intensity at the center of the central bright fringe is 8.50 W/m2. a) Find the maximum number of totally dark fringes on the...

Homework Statement OK, so this is a very basic question but i am uncertain what the relationship is. I know its logarithmic, but i don't know how to draw a conclusion. Here is the question: If you want an amplifier which will give a sound output which is twice as lod as your present 20 W...

I have read about light and polarization. One thing I don't understand though... If you would look through a circular polarization filter, you notice that the light is less intense. But if you look at photons that are unpolarized; they become polarized when they go through the filter. I have...

Hello everyone. From what I've understood, the radiant intensity of a surface is defined as the number of photons emitted by the surface per unit solid angle (steradian) and per second, times a constant (that constant being the mean energy of a photon emitted by this surface). So radiant...

Homework Statement I am try to understand how the value of 1370 watts per metre squared for the intensity of sunlight hitting the Earth has been derived. Is there a way to see this mathematically? Homework Equations I understand about how the intensity is related to Poyntings vector, by...

I have a text that claims that the intensity of the electric field between two parallel plates is independent of the separation distance and depends only on the charge on the plates. Is this correct?

I am trying to model light that (1) exits a multimode fiber (2) passes through a cylindrical lens system and (3) enters a multimode fiber (and yes I know that a cylindrical lens system is not ideal for fiber coupling). The radius of curvature for each of the cylindrical lenses in my system...

Hi, I just wanted some clarification with respect to a few equations relating stress intensity factor to semi-elliptical and quarter-elliptical cracks in solids. The equations I have according to my notes are K_{I_{(\varphi=\frac{\pi}{2})}}=1.12\frac{\sigma \sqrt{\pi a}}{\Phi} and...

I understand the inverse square relationship between sound intensity (I) and distance (r). There was a misunderstanding in physics class today about the mathematical and theoretical relationship between sound intensity and power according to the equation: I = P/4∏r2 Sound intensity is...

Homework Statement The intensity of the sound from a certain source is measured at two points along a line from the source. The points are separated by 11.8 m, the sound level is 68.10 dB at the first point and 60.31 dB at the second point. How far is the source from the first point? d =...

Hello all, I came across this question in mastering physics and simply could not solve it. I asked for the answer to the question and decided to move on.Homework Statement You are standing 1.7m from a 100-W lightbulb. If the pupil of your eye is a circle 5.0 mm in diameter, how much energy...

Since light intensity increases with the number of photons, and the photon can be viewed as energy, would energy be proportional to intensity of light? Also since energy is inversely proportional to the wavelength of light, this would mean that the intensity of light is also inversely...

I am starting to become confused when reading about quantum mechanics and its treatment of photons. I heard somewhere (I can't recall where) that the characteristic intensity of a photon beam was give by I = E/\omega, where \omega is the angular frequency of the beam. However, I can't seem to...

Homework Statement How much acoustic power propagates through a spherical surface (sound source in centre) with radius equal to 1.0m? with radius equal to 5.0m? I = 10^-2 W/m^2 r = 1.0m or 5.0m f = 50kHz t = 2.0*10^-3s IL = 100dB Homework Equations I = P/4∏r^2 The Attempt at a...

I have a problem understanding the intensity of light. Let's assume a monochromatic light of a single wavelength. The energy of the wave is constant and equal to h* f where h is the Planck's constant and f the frequency of the wave. The intensity of this wave is its energy divided by a given...

Hey guys, I've just got a couple of questions about this prelab I need to do for the Double Slit experiment. And just to make sure this is clear (I have no idea whether the method used in this experiment is normal) we have a double slit and a slit blocker. The slit blocker is after the...

Homework Statement The intensity of light I in the fraunhofer diffraction patter of a single slit is I=I0(sin\gamma/\gamma)2 where \gamma=\piasin\theta/\lambda Show that the equation for the vaules of \gamma at which I is maximum is tan\gamma=\gamma well, intensity is...

why is sound heard more clearly in night than at day?

Hey Guys, i'm a first year astrophysics student and i got given this question to answer in a practical report: Examine the spectrum of the planetary nebula derived from the diffraction grating. You will produce a colour rendering of the spectrum together with a graphical representation of...

Homework Statement An electric charge is distributed along an infinite line (2x+3y=7) in xy-plane with density pl = 3uC/m. Find the Efield intensity vector at point P (5,6). Homework Equations E = Integral of pl/ (4*pi*E) * (R - R')/ (R-R')^3 The Attempt at a Solution I just wanted...

Hello everybody, I have some questions: I'm talking only about traveling waves, not standing waves. If a linear polarized electromagnetic wave has electric field amplitude E_0, i know that its intensity is given by I=(1/2) (E_0^2 ) /c that is the Poynting vector averaged over a...