Intensity Definition and 966 Threads

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 The specific impedance of fat, muscle and bone are 1.4 x 106 kg m-2 s-1 , 1.6 x 106 kg m-2 s-1 and 6.5 x 106 kg m-2 s-1 respectively. The linear absorption coefficients in fat and in muscle are 0.24 cm-1 and 0.23 cm-1 respectively. A parallel beam of ultrasound 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?

Homework Statement I am currently studying the optical Michelson Interferometer and I am in need of help with a derivation. The equation I need to derive is that for the intensity of the light arriving at the viewing point. The equation is given below.Homework Equations I(Δ)=I/2 +...

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 =...

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? Know: I = P/A =...

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...

Homework Statement A sheet of charge Ps = 2 NC/m^2 is present at the plane x = 3 in free space, and a line charge Pl = 20 nC/m is located at x = 1, z = 4. a) Find the magnitude of the electric field intensity at the origin b) Find the direction of E at P (4,5,6) c) What is the force per...

Homework Statement A certain loudspeaker system emits sound isotropically with a frequency of 1770 Hz and an intensity of 0.892 mW/m2 at a distance of 5.66 m. Assume that there are no reflections. (a) What is the intensity (in mW/m2) at 30.8 m? At 5.66 m, what are (b) the displacement amplitude...

I have LEDs of 0.7mW, but for my experiments, I want my values to be in light intensity unit - W/cm2. I cannot figure out how to do the conversion.

Hello, I need to calculate intensity of light at a distance of 24 inch from a tubular light source with a light intensity rating specified at 3.6 microwatts/sq.cm. per inch of lamp. The light is a UV light which is to illuminating a cooling coil in air conditioning system. Supposedly there...

Homework Statement Henry and Tom see a flash of lightning and then hear the resulting clap of thunder. Henry measures the sound level of the thunder as 65 dB while Tom, who is 800 m further from the event, measures it as 63 dB. Homework Equations The Attempt at a Solution I_H /...

Hi all, I've got a problem with the circuit of the image. The solution (intensity) is given but i would like to know how to get it... Can anyone help me? [PLAIN]http://img191.imageshack.us/img191/9094/circuitf.gif Thanks!

intuitively, i would say that in a CCD, the photoelectrons are being "created" only by the electric field of the incident light, so that the intensity is proportional to |E_x|^2+|E_y|^2, with the xy-plane coinciding with the CCD plane. But I have several papers here saying that the intensity...

Hey, In x-ray tubes, how come an increase in the voltage results in an increase in the intensity of the electrons. i.e. the no. of electrons emitted per unit time per unit second. Thanks.

Does the timescale over which a charge decelerates determine the energy and intensity of brem photons? Consider two electrons, one is decelerated over a large distance and relatively long period of time. A second electron is involved in fast scattering event and loses its energy relatively...

Sound Intensity-- just need someone to check my work :) Homework Statement While enjoyable, rock concerts can damage people's hearing. In the front row at a rock concert, 5m from the speaker system, the sound intensity is 145 dB. How far back would you have to sit for the sound intensity...

I'm trying to find a mathematical formula between applied tension and resulted magnetic field intensity on an electromagnet. I know that between the voltage and the electric current there is a pi/2 offset, but in practice there is a bit more than actually pi/2 offset probably something that...

I am researching how photon intensity attenuates within matter and am a bit confused by what I have come across. Several sources state that the attenuation of photon intensity within matter is exponential (as a function of depth). The explanation is that photon interactions with electrons in...

Homework Statement Two polarizers are out of alignment by 30°. If light of intensity 3.86 W/m2 and initially polarized halfway between the polarizing angles of the two filters passes through the two filters, what is the intensity of the transmitted light? The Attempt at a Solution Use...

Homework Statement Find the sound intensity level of a thunder bolt, if a person is standing 200 m from the spot it hits. The bolt hits the ground vertically and the height of the bolt is 1500 m. The bolt has an electrical current of 20 kA and a voltage of 30 MV. It discharges thrice, each...

Homework Statement Hi, here is the problem I'm having trouble with: The rms value of the magnitude of the magnetic field in an electromagnetic wave is Brms = 0.137 T. The intensity of this wave is approximately... Homework Equations E = cB I = (ErmsBrms) / \mu0 The Attempt at a...

OK so i know it is possible to double the frequency of a light beam by using second harmonic generation by passing the beam through a non-linear crystal; however i am unclear as to the required intensity of light beam that is needed to achieve efficient conversation. Would it be possible to...

Hi. During daytime sea water having poor solar reflectivity remains warmer than the air. But at times, water has also been found to be colder than air, with the difference being 5-10 degrees C. Can anyone please justify how could that be possible?