Intensity Definition and 898 Threads

These are some of the factors I brainstormed that goes into the functionality of a spotlight: 1) Light output of the light source (measured in luminous flux, if I recall correctly) 2) The reflective potential of the reflectors surrounding the light source 3) The geometry of the reflectors...

what type of circuit would you draw for this? and how would you actually measure the light intensity of an LED. say you had multiple LEDs and you wanted to compare the light intensity of all of them. how would you do this with with circuit?

what is the difference between luminosity, Intensity and flux in particle physics? Some time people use them in similar meanings.

Hello, I have a question regarding Reynolds numbers. As I understand, the higher a Reynolds number, the more turbulent a flow becomes, with Re>4000 considered turbulent. I have a model where I've calculated a Reynolds number of 10^7, and when going to set my model boundary conditions I'm...

I'm not sure if I've understood my textbook correctly. Can you tell me if my current understanding is correct: - in a single slit diffraction there's a wide central fringe which is twice as wide as all the other outer fringes - if we had a double slit diffraction instead of a single slit...

Homework Statement Please help me to solve this type of circuits... I want to find the intensity through each power source and what voltage does the voltmeter indicates. http://iceimg.com/i/f5/1d/2da68fc0a6.png Homework Equations I=I1+I2 The Attempt at a Solution don't know

Homework Statement What is the intensity of the electric field that can be transmitted through N linear polarizers if the polarization of the initially linear polarized light is to be rotated 90 degrees? Homework Equations I=IoCos^2x The Attempt at a Solution I am seeing like...

Homework Statement When deriving the intensity of an electromagnetic wave in my textbook, there was a part I didn't quite get. It's how I = Watts/m^2 becomes I= u c My textbook gave an example of a electromagnetic wave through a cylinder, with cross-section area A. In 1 second it would...

i was trying to verify the '8 years 7 months 6 days' myth/fact that states that you would have you scream for that much time to produce enough energy to warm up a cup of coffee. i assume that an average human screams at 80 dB.if i have to calculate the power,do i have to take the area of mouth...

My textbook says that in the equation β= 10log(I1/I2), I1 in most cases is the threshold of hearing (1.0x10^-12). Just out of curiosity, when is I1 not the threshold of hearing?

Homework Statement I am having a hard time discerning the difference between radiant intensity and irradiance. I searched PF and found this distinction, but am still confused. Radiance is the power from the source per area into a certain solid angle. Irradiance is the power onto a...

Hi Guys, A basic oxygen furnace is very large 400 ton vessel that steel is refined in. during the refining process oxygen is blown into the steel. during this process there is a flame at the mouth of the furnace, this is what I am interesting in. during the process the flame changes in size...

Homework Statement Homework Equations The equation that is already given + (maybe) I is proportional to A2f2. The Attempt at a Solution I took the square root of 8, 8 being the Amplitude and I being proportional to the square of A. (I make the constant of proportionality 1)...

Hello Everybody, I'm trying to plot the frequency spectrum of RIN using Matlab. I've the following code function p=rateblock tau_s = 3e-9; N0 = 1e24; A =1e-12; P0 = 1/(A*tau_s); TSPAN = 0:1e-2:10.23;; Y0 =[0 0]; [T,Y] = ODE45(@rate_equation,TSPAN,Y0); subplot(2,1,1)...

Homework Statement A 285Hz sound wave is directed into one end of a trombone slide A microphone is placed at the other end to record the intensity of sound waves that are transmitted through the tube. The straight sides of the slide are 80cm in length and 10cm apart with a semicircular bend...

There are materials which block laser beams (or light globally) or weaken its intensity via shading i.e. a beam must have crossed a specific energy barrier in order to pass this shading where beams with less energy will fade and won't pass. The question is, is there a material or a type of...

Hi guys, I cannot understand why we need to correct cosray intensity with pressure and why the equation that describes the phenomenon is I=Io*exp(-a(Δp))? I want to know the phsyical meaning of this(i assume,experimental) result... Thank you...

Homework Statement Describe the far-field intensity distribution if f(x',y') = circ(\frac{\rho}{D}) cos(\frac{k \theta x'}{2} where \rho = \sqrt{x^{2} + y^{2}}. Homework Equations The Fourier transform of the circ function was given to us earlier: \textbf{F} [ circ(\frac{\rho}{D})...

Homework Statement The intensity produced by a long cylindrical light source at a small distance r from the source is proportional to a)\frac{1}{r^2} b)\frac{1}{r^3} c)\frac{1}{r} d)None of these Homework Equations I=\frac{dF}{dω} I is the intensity, dF is the luminous flux of the...

Homework Statement Suppose sound wave is emitted uniformly in all directions by a speaker. At a distance of 1.1m, the amplitude of it sound is 1.2x10^-8m What is the amplitude of sound at a distance of 1.7m?The Attempt at a Solution What I'm confused is why does the amplitude of sound change...

Homework Statement Laser light of wavelength λ is incident onto a pair of narrow slits of width a and spacing dWrite down an expression for the intensity as a function of angle of the angle measured from the central axis, θ, in the far-*‐fieldHomework Equations The Attempt at a Solution I...

Homework Statement Given that: TI1 + TI2 = 70 dB TI2 + TI3 = 80 dB Find TI1 + TI2 + TI3Homework Equations TI = 10 log (I/Io)The Attempt at a Solution From that two equations, I got: I1.I2 = 10-17 I2.I3 = 10-16 I1.I22.I3 = 10-33 Then stuck...

Homework Statement Let the regions 0 < z < 0.3 m and 0.7 < z < 1.0 m be conducting slabs carrying uniform current densities of 10 A/m^2 in opposite directions. Find H (the magnetic field intensity) and different z positions. Homework Equations Biot-Sarvot Law: H = ∫ (I dL X r)/ (4∏R2)...

Hi Let's stick to the classical limit. We have 2 monochromatic light waves of same intensity. Let's say one is blue and one is red. Now this means the individual photons of the blue light have more energy(obviously, higher frequency) and the red light photons have lower energy. But since...

Hello. I have been studying interference and diffraction and one doubt has appeared. When you consider the double slit experiment forgeting the effects of diffraction you get the following equation for intensity I^{}=4I_{0}cos^{2}(\frac{πdsin(θ)}{λ}) where d is the distance between the...

Homework Statement The circular region, ρ < a, z= 0, carries a uniform surface charge density ρ ( subscript s). Find E at P(0,0,h), h > 0. Homework Equations Coulombs law Field of a line charge and field of a sheet charge.The Attempt at a Solution I'm not sure what they are asking for , but my...

Hi all, Would really appreciate some help on this problem I can't seem to figure out. Brown coal has an energy content of 15MJ/kg, carbon content 65% by weight, burning in a 30% efficient steam power plant. Calculate the CO2 emission intensity (kg CO2 emitted/kWh delivered).Assume complete...

Homework Statement A choir made up by 100 voices (i.e. 100 singers), during the execution of a song, reaches the sound intensity of 100dB. Assuming that all singers sang with the same intensity, the sound intensity of each singer was...? Homework Equations ΔS=10.log(I/Io) The...

First, I’d like to say that this is not homework, but my research work. I’ll be very appreciated if someone could help me to address this issue, many thanks in advance. My experimental purpose is to generate uniform electric field inside microchannel by externally-applied electric field...

I am new here and asking question for the first time of course. My question is very simple. Does electric field intensity exist 'inside' a wire carrying current? Please explain the answer.

http://www.google.com/patents/US685012?printsec=abstract#v=onepage&q&f=false Is this system used today in electrical transmission? If not why not?

I have measured photoluminescence (PL) and light absroption spectra of some transtion metal oxide nanostructures. The PL intensity increases remarkably by decreasing the size of nanostructures. However, the intensity of absorption vary litte. Is there any relationship between the PL intensity...

I have looked through my optics textbook and many websites about single-slit diffraction. They all end up deriving an equation that looks something like this: I = I0*(sinc(B))2, where B = (1/2)*k*b*sin(theta), k = wavenumber, b = slit width. I don't know if there's something I'm not...

Homework Statement The intensity of a sound wave at a fixed dis- tance from a speaker vibrating at 1.31 kHz is 0.894 W/m^2. Determine the intensity if the frequency is increased to 2.33 kHz while a constant dis- placement amplitude is maintained. Answer in units of W/m^2 Homework...

Hi I am looking at a bunch of atoms in a homogeneous magnetic field, irridiated by a monochromatic EM wave. I am trying to figure out how to intensity pattern of the emitted light by the atoms looks. Case 1) I have attached a picture of the situation called "case_1.jpg". It is very clear...

The time averaged norm of the Poynting vector of this electromagnetic field (elliptically polarized light): \begin{split} \bar{E}(t,\bar{x})=&(\bar{E}_{0x}+\bar{E}_{0y}e^{i \delta})e^{\bar{k}\cdot\bar{x}-\omega t}\\ \bar{B}(t,\bar{x})=&\frac{1}{\omega}(\bar{k}\times\bar{E}(t,\bar{x}))...

A proton is placed in an electric field of intensity 700 N/C. What is the magnitude and direction of the acceleration of this proton due to this field? in a google I found that 1 proton= 1.6022 x 10 ^ -19 and 1.6726 x 10 ^ -27 kg so I first get the force : F= q*E f= (1.6022 x 10 ^ -19...

It seems to me that luminous intensity should really be put in terms of energy, not a special unit (which itself is based on some arbitrary specification of energy.) The other 5 units and Avogadro's number should be the only fundamental units.

Homework Statement Two long parallel wires are a center-to-center distance of 4.60 cm apart and carry equal anti-parallel currents of 4.40 A. Find the magnetic field intensity at the point P which is equidistant from the wires. (R = 4.00 cm). Homework Equations magnetic field for a...

Homework Statement By direct calculation, derive and expression for the wavelength λ(max) at which blackbody radiation intensity is a maximum [b]2. Homework Equations Planck's law for the intensity distribution of blackbody radiation as a function of wavelength λ and the blackbody...

Our physics teacher gave us a formula to calculate intensity, she didn't really specify what intensity, it should be related to sound. I = intensty A = amplitude P = Density F = frequency V = velocity pi = 3.14 she said I = 2*(pi)^2*A^2*P*F^2*V I can't find anything like this in books or...

I'm working with a setup involving a collimated laser (Thorlabs model CPS180), two polarizers, a beam splitter, and 2 photo-diodes. While measuring the intensity of the laser via LabView, without changing any of the components, I find the intensity varies by 0.2mV for the first hour of...

Hi, Suppose we have the x and y components of the electric field being described as (E_{x}e^{i(kz-\omega t)}, E_{y}e^{i(kz-\omega t +\phi)}), what is the intensity? I think the correct answer is E_{x}^{2} +E_{y}^{2} + 2E_{x}E_{y}\cos\phi. However, I am not sure how to deal with this using the...

Can a lux meter measure infrared intensity like it does for the visible light? I read from somewhere that it cannot. If you have an IR illuminator on in the dark and hold up your 'regular' lux meter to it, it will likely register 0 - an unhelpful and misleading result. I'm just wondering if...

Homework Statement The sound intensity level of a certain sound source is measured by two listeners located at different positions along a line from the source. The listeners are located on the same side of the source and are separated by 34.8 m. The listener that is closest to the source...

Homework Statement Sound 1 has an intensity of 39.0 W/m^2. Sound 2 has an intensity level that is 2.5 dB greater than the intensity level of sound 1. What is the intensity of sound 2? Homework Equations I=energy/area*time β=(10dB) logI/Io Io=10^-12 W/m^2 The Attempt at a Solution...

In viewing a derivation of the formula describing the intensity of the interfering waves, I noticed how the electric field components were combined - one from slit a, the other from slit b. The intensity is then proportional to the square of this value. But this would mean that two in phase...

Homework Statement A randomly polarized beam of light hits a water surface at Brewster angle. What is the intensity of the transmitted and reflected beams? The refractive index of water is n = 1.33 Homework Equations The Attempt at a Solution Since the light is randomly polarised...

1. Homework Statement A 200 mW horizontally polarized laser beam passes through a polarizing filter whose axis is 25 degrees from vertical. What is the power of the laser beam as it emerges from the filter? P=mW 2. Homework Equations I0cos2(theta) I≈E0cos(theta) I=E0cos2(theta)...

OK, so i have a question about the nature of light, in the context of the photoelectric effect. So when photons are incident on a metal, given that they have a high enough frequency they can cause electrons to be emitted from the metal. Now i know that intensity of light is to do with the...