What is Intensity: Definition and 963 Discussions

Sound intensity, also known as acoustic intensity, is defined as the power carried by sound waves per unit area in a direction perpendicular to that area. The SI unit of intensity, which includes sound intensity, is the watt per square meter (W/m2). One application is the noise measurement of sound intensity in the air at a listener's location as a sound energy quantity.Sound intensity is not the same physical quantity as sound pressure. Human hearing is sensitive to sound pressure which is related to sound intensity. In consumer audio electronics, the level differences are called "intensity" differences, but sound intensity is a specifically defined quantity and cannot be sensed by a simple microphone.
Sound intensity level is a logarithmic expression of sound intensity relative to a reference intensity.

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  1. N

    X-ray crystallography; intensity peaks vary with voltage

    Homework Statement I have done a simple lab experiment to find the lattice constant for NaCl. Using a diffractometer, radioactive counts were measured as a function of crystal orientation angle for electron voltages of 20 and 30 kV. The average lattice constant found wasclose to the accepted...
  2. R

    B Directed Energy: Low Intensity Applications

    Mostly used for weapons, can sources of directed energy be contained at low intensities? In theory, could it be set to specific wavelengths, frequencies, intensities or whatever to say remove particles of lower cohesiveness from other surfaces or materials?
  3. doktorwho

    Velocity vector and velocity intensity

    Homework Statement Given the velocity vector in the polar coordinates, ##\vec v=-awsin{wt}\vec e_r + awcos{wt}\vec e_\theta## determine the average velocity vector and velocity intensity over a time period ##[0, \pi/2w]## Homework Equations 3. The Attempt at a Solution [/B] For the first part...
  4. O

    Sunlight, Intensity, electric field RMS

    Homework Statement Estimate the rms electric field in the sunlight that hits Uranus, knowing that the Earth receives about 1350 W/m2 and that Uranus is 19.2 times farther away from the Sun (on average) than is the Earth. Homework Equations I=cεoErms2 E=V/d The Attempt at a Solution Eearth=V/d...
  5. S

    Intensity of Diffraction Pattern

    Homework Statement An interference pattern is produced by light with a wavelength 580 nm from a distant source incident on two identical parallel slits separated by a distance (between centers) of 0.480 mm . Let the slits have a width 0.320 mm . In terms of the intensity I_0 at the center of...
  6. Pambos

    Intensity of sound wave and energy

    Homework Statement A sound wave with intensity 2x10^(-3) W/m^2 is perceived to be modestly loud. Your eardrum is 6.0 mm in diameter. How much energy will be transferred to your eardrum while listening to this sound for 1.0 min? Homework Equations P=IA=(intensity)(area) =2x10^(-3) * (pi...
  7. F

    I Hydrogen electron transition intensity 2p - 1s

    Let's say we have a transition from state 2p to 1s of an hydrogen atom's electron. The intensity radiated by the electron is given by I = 4/3 ωfi4 e2/c3 |< f | r | i >|2. If we take the the | 2 1 1 > → | 1 0 0 > transition for example, we must compute the following integral : < f | r | i > =...
  8. G

    Intensity of EM wave independent of frequency?

    Hi. I'm a bit puzzled that the classical formula for the intensity of a monochromatic, linear EM wave $$I=\frac{1}{2}\cdot c\cdot \varepsilon_0\cdot E_0 ^2$$ seems to be independent of frequency whereas I find for the energy of a mechanical wave (e.g. on a string with total mass ##M##)...
  9. H

    Intensity at a point on the screen

    Homework Statement Monochromatic light of wavelength 592 nm from a distant source passes through a slit that is 0.0290 mm wide. In the resulting diffraction pattern, the intensity at the center of the central maximum (θ = 0∘) is 3.00×10−5 W/m2 . What is the intensity at a point on the screen...
  10. M

    Radio Broadcast Antenna Peak Intensity

    Homework Statement A radio broadcast antenna is located at the top of a steep tall mountain. The antenna is broadcasting 104.3 FM (in Megahertz) with a power of 5.00 kilowatts. What is the peak intensity of the signal at a receiving antenna located 25.0 km away? Homework Equations Honestly...
  11. nso09

    Relationship of slit, wavelength, and intensity

    Homework Statement Coherent electromagnetic radiation is sent through a slit of width 0.01 mm. For which of the following wavelengths will there be no points in the diffraction pattern where the intensity is zero? A. Blue light of wavelength ##\lambda=500 nm## B. Infrared light of wavelength...
  12. DoobleD

    Light intensity independant of frequency and E = hf

    Isn't it weird that light intensity (which is time average of Poynting vector) doesn't depend of the light frequency, while the energy of a photon does ? From E = hf it seeems that frequency would have an impact of light energy flux (even time averaged). But intensity, which is a (time...
  13. Y

    B No intensity drop if slit width is negligible in double slit

    In our textbook, it says that the intensity of a double slit interference pattern stays the same if the slit width is negligible. I do not understand this concept. As far as I am concerned, intensity should decrease as the circle of diffraction increase, as intensity is work per area, and the...
  14. R

    Is pixel a representation of intensity for light at a given location?

    Is pixel a representation of intensity for light at a given location?
  15. senobim

    Calculating Scattered Light Intensity at Different Wavelengths

    Homework Statement Light is scattered in cuvette by Reyleigh scattering, and is measured by monochromator. Light intesity is given by I(ν)=I0ν1/2 relationship What is scattered light intensity at λ = 400nm if at λ = 800nm is I800? Homework Equations Scattered light intensity is proportional...
  16. Ryan Hardt

    Calculating Uncertainty for a Chain of Trig Functions

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  17. H

    Question about Inverse Square law and sound intensity

    Homework Statement For school, I have to make a task about sound intensity and the distance to the sound source. I have to prove that the relation between these two is known as the inverse square law _1/ I_2 = ( _2/_1 )². Does someone know how I can plot the inverse square law or prove that it...
  18. toforfiltum

    Describe curve to reduce field intensity in fastest time

    Homework Statement Igor, the inchworm, is crawling along graph paper in a magnetic field. The intensity of the field at the point ##(x,y)## is given by ##M(x,y)=3x^2+y^2+5000##. If Igor is at the point ##(8,6)##, describe the curve along which he should travel if he wishes to reduce the field...
  19. Alfreds9

    Maximum light intensity underwater during seasons?

    Hi, I was thinking if maximum light intensity underwater during seasons changes somehow. I firstly thought about considering monthly solar irradiance (http://neo.sci.gsfc.nasa.gov/view.php?datasetId=CERES_INSOL_M) however I thought this would have been biased at certain latitudes due to...
  20. A

    Logarithmic scale for the Laser Intensity.

    I drawed a relation between the growth rate of the material to the laser intensity. After drawing, My professor told me that I must convert both values of the growth rate and the laser intensity to their values in the logarithmic scale. I don't know how. May I get a help.
  21. G

    How can I correlate the light intensity and energy?

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  22. G

    I Photon Interval vs Areal Density for Changing Intensity

    When one reduces the intensity of let's say, an incandescent bulb (by varying the resistance, as seen in many homes), which decreases more, the photon frequency (not related to wavelength, but the time interval between photon emissions) or the areal density of the photons? To what extent does...
  23. S

    Problem on Doppler effect and sound level

    Homework Statement A source emits a spherical sound wave at frequency ##f=110Hz## with power ##P=1 W## in a solid angle of ##2 \pi sr##. An observer moves with velocity ##v_{oss}=108 km/h## towards the source. Determine the sound intensity level received by the moving observer. Homework...
  24. S

    Doppler shift and change in intensity of a sound wave

    How are the intensity of a sound wave and the Doppler shift of frequency related togheter? That is, if the source or the observer are in relative motion, how does the intensity change? For a sound wave $$I=\frac{1}{2} \rho \omega^2 A^2 c=2 \pi^2 \rho f^2 A^2c$$ (##c## is sound speed, ##\rho##...
  25. G

    How does Turbulence Intensity affect drag and flow separation?

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  26. victorhugo

    I Hyperfine splitting and relative intensity of spectral lines

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  27. EmilyBergendahl

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  28. Sean Jackson 01

    Relationship between power usage and time

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  29. Sean Jackson 01

    I What is the correct terminology for intensity and effort in exercise?

    Hello all, Great site...such a cool resource. I am a fitness coach...as in any profession basing what we do on solid science is vital...and exercise practice goes "some way" to doing this...but it has its flaws. Hopefully a coach will talk about work, power and torque etc correctly, and have...
  30. T

    Deriving Laser Intensity proportional to N Molecules

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  31. ciso112

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    Homework Statement Very thin wire bent into the shape of a quarter-circle with the radius R is uniformly charged with electric charge q. Calculate the potential and intensity of the electric field at point A, which lies on a line perpendicular to the plane of the semicircle and is passing...
  32. I

    Intensity of Light Through Pentaprism Including Reflections

    Homework Statement A pentaprism is a five-sided reflecting prism used to deviate a beam of light by 90◦ without inverting an image. Pentaprisms are used in the viewfinders of SLR cameras. (a) What prism angle β is required for a normal-incidence beam from the left to exit the bottom surface at...
  33. gsmtiger18

    Phase shift of light incident on 2 slits

    Homework Statement Light of wavelength λ = 450 nm is incident upon two thin slits that are separated by a distance d = 25 μm. The light hits a screen L = 2.5 m from the screen. It is observed that at a point y = 2.8 mm from the central maximum the intensity of the light is I = 55 W/m2. a)...
  34. ing_it

    Intensity of an electric field near a wire -- With and without Gauss' Law

    Homework Statement We have a wire of the length L=0.2m which is uniformly charged with a linear density of Lambda = 3nC/cm. Find the intensity (E) of the electric field in point A1 whose perpendicular distance from the wire is a=0.05m. The wire is in a vacuum. Compare the intensity with the...
  35. T

    I Different Blackbody Intensity Peaks, how do we measure it?

    For the Blackbody Spectrum, there are two versions of the formula, one for wavelength and the other one for frequency: The peak intensities for both occur at different wavelengths (or frequencies).How do scientists measure the spectral radiance of blackbodies? Are there TWO types of...
  36. W

    Single Slit Diffraction Intensity

    Homework Statement A narrow slit is illuminated by a collimated 633-nm laser beam as shown in the figure below. This produces a diffraction pattern on a screen, which is 6 m away from the slit as shown in the figure below. The distance between the centres of the first minima outside the central...
  37. JohnGaltis

    Conceptual Question about Polarisation and Intensity/

    Homework Statement Consider a beam of unpolarised light incident onto air from a crown-glass with a refractive index of 1.52. Given that the incident light intensity has a power of 10mW, find the minimum incident angle when the power of the refracted light becomes zero. Homework Equations I...
  38. person_random_normal

    Incoherence of Light Sources: Phase Difference & Intensity

    Why will it happen so that-two light sources such that the ''phase difference between the two vibrating sources changes rapidly with time, we say that the two sources are incoherent and when this happens the intensities just add up '' assuming that the wave characteristics of light are significant
  39. I

    Calculation of peak acoustic intensity (in water)

    If we know the max. pressure (p) is 2.5 MPa and T = 20 C. Peak intensity, I = p^2 / rho * c where rho = density of water: 0.9982E03 kg/m^3 and c = speed of sound in water: 1482.3 m/s at 20 C I = (2.5E06 [Pa])^2 / 1.4796E06 [kg/m^2/s] = 4.2241E06 W/m^2 Is this correct?
  40. T

    I Exploring the Mechanisms of Enhanced Radiation Intensity in Superradiance

    I was reading through a paper and it says that super radiance enhances radiation intensity. That this can be understood by the fact that when the distance between neighboring atoms is much smaller than the wavelength of radiation, the photon emitted by one atom is seen to be in phase by...
  41. Garlic

    I Intensity of the background neutron radiation

    Hello everyone, What is the average intensity of the background neutron radiation?
  42. Garlic

    I Detecting low intensity neutron radiation

    Hello everyone, Is it practically possible to detect a neutron source with an intensity of 0.1 Bq and each neutron having nearly 10MeV energies (and differentiate it from background neutron radiation)? If that's possible, what kind of equipment can be used? Do you need extremely sensitive and...
  43. L

    Help Needed -- Near Infrared Intensity Sensor

    Hello, I am part of a synthetic biology team whose goal is to modify immune cells to respond to an incident wavelength of 670-702nm and emit a near-infrared wavelength of 650-900nm(to be determined). My goal is to create a sensor that will be able to detect this emitted wavelength through...
  44. L

    Maximize output intensity -- laser

    Homework Statement Show that the output coupling that maximizes output intensity (Iout=0.5tIsat(2gl/(t+s) -1) is given by t=sqrt(2gls)-s Homework EquationsThe Attempt at a Solution Iout/Isat=0.5tgl/(t+s)-0.5t 1=0.5tgl/(t+s)-0.5t 1+0.5t=0.5tgl(t+s) (t+s)+0.5t(t+s)=tgl this gives me a really...
  45. ckyborg4

    Is there any relationship between light intensity and angle

    Homework Statement I'm working on a project right now, which uses laser beams and part of the project requires me to find a mathematical model which relates angle of projection to the intensity of the light. Does anyone know of an equation(s) which relates the intensity and angle together...
  46. P

    B Why Does Wave Interference Alter Intensity Distribution?

    Lets consider two waves, the intensity of each wave is proportional to the square of their amplitude, now why the intensity of the sum of the two waves is not the sum of each intensity but is proportional to the square of the sum of the amplitudes? (i know it on the math side and i can...
  47. E

    Young's Double Slit - Low intensity

    Homework Statement Having recently completed an experiment on Young's double slit experiment for both high and low intensity light; I am having trouble writing conclusions in the report. In one part of the experiment I know I was firing only one photon at a time down the tube, and I achieved an...
  48. T

    Definition of intensity in radiation

    Hi, I recently read that as temperature increases, atoms move faster and have higher frequencies, shorter wavelengths and more intense radiation. What does intense mean? Does it mean in a substance there are a greater percentage of atoms emitting at higher frequencies or does it mean another...
  49. A

    Relationship among Intensity, Frequency, and Current

    Hi all, I am really confused about the relationship among these three properties and I cannot find an answer satisfying enough.. If frequency of incident light increases but intensity remains the same, the photocurrent will decrease. Does this mean that the new curve on the current vs. voltage...
  50. P

    What is the Intensity of Seidel Point?

    Hello I have to prove that the intensity of seidel point is equal to ##I_{sp}=\frac{8}{\pi^2} I_o## I didn't get any other information only that there is an integration in this prove. Hope you can help me. It is enough for me if you only give me link or the name of this prove.
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