Intensities Definition and 32 Threads

Hello, I've been trying to wrap my head around why, if given the sound pressure levels (dB1 and dB2) of two uncorrelated sounds, if you want to sum them together, you sum their intensities using the equation: 10 x log10(10^dB1/10 + 10^dB2/10). Likewise, if you want to average them, you average...

Hi. I'm really stuck with this problem and would appreciate some help. For example, if i take the total intensity from the ##^2\text{P}_{3/2}## level, i get ##a+b##. Since ##b## is 9 times larger than ##a##, i get that the total intensity is ##10a##. This should then be proportional to the...

Homework Statement The decibel scale of loudness is L = 10 log##\frac{I}{Io}## where I, measured in watts per square meter, is the intensity of the sound and Io= ##10^-12## watt/m 2 is the softest audible sound at 1000 hertz. Classical music typically ranges from 30 to 100 decibels. The human...

Homework Statement The table gives the theoretical relative intensities in LS-coupling for all possible ##^3F – ^3G## transitions. a) Use this data to verify the sum rules for LS-intensities in a multiplet. b) Use the sum rules to derive the relative intensities in a ##^2D – ^2F##...

Hi. Has anyone already done the work to back out the standard luminosity function so I can go from lumens at a particular wavelength to radiant flux in Watts? I have visible LED spec sheets with optical characteristics in lumens and I want to calculate the outputs in W. My NIR LED has specs in...

A question about the relation of light intensities to the actual time-dependent EM field: Suppose I have a system where the functions ##\mathbb{E}(\mathbf{r},t)## and ##\mathbb{B}(\mathbf{r},t)## (time and position dependent electric and magnetic fields) are known. I would like to have an...

Homework Statement Person A, who is 1.5 meters away from me is speaking to me at a decibel level of 25dB. How loud does person B, who is 15 meters away from me need to speak in decibels to submit me to the same intensity of sound? Homework Equations Ia/Ib=rb^2/ra^2 ∆dB=10log(Ia/Ib) The...

From what I understand, in the equation P=\sigma AT^4, P is the power output of the star which is the energy radiated per second in EM radiation of all frequencies, and I think luminosity is also defined as the energy radiated per second in EM radiation of all frequencies. Therefore luminosity...

GaAs crystal structures have basis atoms: Ga: (0 0 0), (0.5 0.5 0),(0.5 0 0.5),(0 0.5 0.5) As: (0.25 0.25 0.25),(0.75 0.75 0.25),(0.75 0.25 0.75),(0.25 0.75 0.75) i'm trying to find intensities at all of its plane, using this equation: I = (F^2)*m*Lf (m= multiplicity, Lf=lorentz factor)...

Hello everyone ! I am currently reading a paper about crystal properties of R2CuIn3 where R=Tb,H0, Er. It states : 1.that based on bibliography they are crystallized in the hexagonal system P6/mmc. With the use of POWLS software , it was found that there was a second phase Cu2In , so its...

What decibel increase does a hearing aid produce if its sound gathering area is 900cm^2, the area of the eardrum is 0.5cm^2, but it only has an efficiency of 5% in transmitting sound to the eardrum? I know sound level = 10log(final intensity/initial intensity), but we've only been given areas...

Homework Statement This isn't really a coursework question, but I thought this might be the best place for it. I have some data on two different CO line emissions from an object. Can I work out the temperature of that object by using the ratio between the intensities of the two lines, and...

Consider a fixed sound of intensity level SIL1 = 70 dB and another (of different frequency) whose intensity level takes on the series of values SIL2 = 50, 60, 70, 80 and 90 dB. (a) To the nearest dB, what is the level of the combined sound in each case? (b) Make a general statement about the...

Would the drop time of two parachute be the same if the wind intensity they experience is different? (Assuming everything is the same). I know the fact that the wind caused them to fall sideways would not cause a difference since the vertical height is the same. Could anyone please tell me...

Homework Statement 1. Question : A point source emits 34.0 W of sound isotropically. A small microphone intercepts the sound in an area of 0.510 cm2, 185 m from the source. What is the sound intensity at that distance? What is the power intercepted by the distance? Homework Equations...

Homework Statement For two equal-amplitude waves of nearly equal frequencies w+d/2 and w-d/2 (at a fixed position x), you have shown that the intensity exhibits \beats" which for d = 2pi Hz can be perceived directly by the ear, even though the main frequency is perceived only through the...

Hi, I'll start with the background so perhaps you can understand my problem better. I want to write some requirements for diffraction with electrons. I know that typically an electron diffraction pattern would need ~1e6 electrons, I could justify this because I also know (and can show...

Hi- I'm trying to calculate the effect of a magnetic field on some spectral lines. I know that each energy level will split into 2J+1 sub levels (each denoted by Mj). I can calculate the energy level splitting and using the selection rules (dJ = 0, +/-1, dMj = 0, +/-1, dL = 0, +/-1), I...

Hello, I am looking for a software that will allow me to look at the intensity of white light on a picture and display it like a histogram. Any help would be appreciated. Thanks,

Homework Statement Using an intensity of 1 × 10-12 W/m2 as a reference, the threshold of hearing for an average young person is 0 dB. Person 1 and person 2, who are not average, have thresholds of hearing that are β1 = -5.00 dB and β2 = +12.0 dB. What is the ratio I1/I2 of the sound intensity...

(A laser monochromatic laser is shone in from the left, that's E_{in}.) [PLAIN]http://img820.imageshack.us/img820/6184/beamsplitter.png In the lecture notes, it says that: E_{out1}=rE_2+tE_1, where E_1=-rE_{in}e^{i\phi} and E_2=tE_{in}e^{i\phi} I don't really understand the signs...

When you work with spectra, recorded with a detector or a Fourier Transfer Spectrometer, I hear that quantitative intensities is hard thing to measure and that you deal with relative intensities or relations. A few questions about this: Why is it hard to measure quantitative intensities...

When a charge is in motion then what kind of field/fields sorround it on which factor it,s strength depend?

Homework Statement What is the sound intensity 2.5m away from a 50W speaker? (Assume sound is spread out in a sphere) The intensity level 12.0m from a loudspeaker, placed out in the open, is 100 dB, what is the acoustic power output (in Watts) of the speaker? Homework Equations I...

Homework Statement When sounded separately, two identical car horns produce sound intensities at your ear in the ratio 6:1. If the nearer car is 8m from you, how far from you is the more distant car? Assume uniform spherical wavefronts. Homework Equations Intensity=P/4x(3.14)"pi"x...

My friend edits grade school textbooks and often has science questions. While I pretty much know the answers, I like to get them verified from more reliable sources. This is once such question asked: This was my response: True? I mean is this why Earthquakes are measured as magnitudes...

Homework Statement I need to find the ration of the intensities of two sounds if one is 12 dB higher than the other ? Homework Equations I am not sure The Attempt at a Solution I took the inverse log of 12 and multiple the answer with ( 1 * 10^-12) to find I = 1.584 *...

Im dong the zeeman effect for Mercury trasitions 3S1 --> 3P0/1/2 (Violet, Blue and Green lines). I've taken CCD pictures of all lines in a weak B field and with polaroid placed parallel and perpendicularly, and produced graphs of pixel value v column number (intensity v horizontal position)...

Does anyone know how to solve this ? A group of people were exposed to 114 dB music for 60 minutes. Eleven of the 20 subjects showed a 17 dB reduction in hearing sensitivity at 4000 Hz. What is the intensity corresponding to the threshold of hearing for these people ? ( in W/m^2) thanks

Can anyone help me with how you would solve these? i am lost... 1.) Soudn 1 has an intensity of 380 W/m^2. Sound 2 has an intensity level of 2.5 dB greater than the intensity level of soudn 1. What is the intensity level of sound 2? 2.) A siren produces a soudn of 120 dB at 2m. Find the...

Greetings all--I have a relatively basic question regarding waves: For coherent waves, the amplitude of the two waves add (\psi(x) + \phi(x) ) and the resulting intensity is the square of this: (\psi(x)+\phi(x))^2, or \psi(x)^2 +2\psi(x)\phi(x)+\phi(x)^2 However, if youre superimposing...

a 10^4 kg spaceship with a perfectly reflecting mirror is pushed by a laser beam with an accel of .3% g ( Earth's gravity). what is the power of the laser beam? [note:intensity*A = power] not sure what the perfectly reflecting means...but maybe someonce can help...