Intensity Definition and 898 Threads

4. Sound intensity is inversely proportional to the square of the distance from the source The further from the source you are, the less intense the sound. Suppose the sound intensity is 20 watts per square meter. (W/m^2) at 8 meters. What is the sound intensity at 4 meters...

Greetings everyone. I'm working on a project that requires the very accurate measurement of distance varying between 0.500'' and 0.050''. I need to measure the distance within at most 0.010'' tolerance and give the value digitally. The read-rate is once every second. I'm on a very tight budget...

Homework Statement A square with each side of 5 cm in length.Now if 4 parallel wires in each 4A current is flowing were placed on the vertex of the square.How can I find the center of the square of the magnetic strength? Homework Equations I am not sure what equation should be used.If I knew I...

I am calculating the light intensity of Mercury. I was given the average distance from the Sun in AU's which is 0.39. Using the formula (1/(d^2)), I solved for the light intensity relative to Earth which I found to be 6.57. I need to find the light intensity in (w/(m^2))

An Interference pattern is produced by light of wavelength 490nm from a distant source incident on two identical parallel slits separated by a distance (between centers) of d=0.630mm. a) If the slits were very narrow what would be the angular position theta1 and theta2 of the first and second...

Homework Statement Plane polarised is incident normally on a polerizer which can rotate in plane perpendicular to light. The intensity of of incident light is 8W[m][/-2] and transmitted intensity is 2W[m][/-2] if polerizer is rotated 90 deg what is the new transmitted intensity Homework...

Homework Statement When the resistor is R1, in the circle there is the intensity I1 and when the resistor is R2, the intensity becomes I2.Find emf and the inner resistance.[/B] Homework Equations I=emf/R+r The Attempt at a Solution I1=efm/R1+r I2=efm/R2+r efm is equal I1*(R1+r)=I2(R2+r)...

Homework Statement At the vertices of a triangle there are + 5C, -7C, -3C of charge respectively. What is the electric intensity and direction at its orthocentre? Homework Equations Each side of the triangle is 1 mm in length. The Attempt at a Solution [/B] I failed to find the distance of...

I am not sure what intensity actually looks like and means for light. Does this mean that ex red photon, that there are more than one photon that are superimposed on each other hitting the same spot?

I understand that radio waves have very low frequency, which means it is not ionizing as gamma and ultraviolet are, but while browsing the web, it seems that there are mixed point of views on its potential hazard to human health. Hmm, if it is dangerous, why? Does it have to do with intensity...

Homework Statement A cone of height H and base radius A is charged with charge Q uniformly distributed in all its volume. Find electrostatic field intensity at the top of the cone. DATA: H, A, Q Homework Equations E=ρ/(4πε0) ∫Ω dΩ/R2) and R is a vector (rr^+zz^) r^ and z^ are versors The...

Homework Statement Plot the following function in maple (any graphics software): I_\theta = I_m (cos (\beta))^2 \left( \frac{sin(\alpha)}{\alpha} \right)^2 Homework Equations Range = -20 degrees to 20 degrees \beta = \frac{\pi d}{\lambda} \sin(\theta) \alpha = \frac{\pi a}{\lambda}...

I observed following phenomena today: in my room with some lightings, there is a stuff toy placed in front of a wall. The ambient lighting doesn't cause any shadow on the wall currently. Now, I switched ON a torch and pointed it to a stuff toy which was kept in front of a wall and a shadow...

What is the intensity in W/m² of a laser beam used to burn away cancerous tissue that, when 94.0% absorbed, puts 539 J of energy into a circular spot 2.11 mm in diameter in 4.00 s?? I've tried a couple different equations and I keep getting the answer wrong. This is due tonight, I'm super...

Homework Statement Here is the problem: http://faculty.kfupm.edu.sa/PHYS/kuhaili/doppler_problem.htm {Mentor's edit: Here's the text copied from the url: A fire engine moving to the right at 40 m/s sounds its horn ( frequency 500 Hz ) at the two vehicles shown in the figure. The car is...

Homework Statement A beam of wavelength 600 nm has initially an intensity profile of Gaussian shape with a fwhm of 1 mm. Determine the intensity profile and fwhm 10 meter away.Homework Equations FWHM = λ/(2NA√(1 + I/Is)) The Attempt at a Solution [/B] FWHM1 = 1mm = 600 nm/(2NA√(1 + I/Is))...

problem statement, all variables and given/known data A finite sheet of charge, of density ρ=2x(x2+y2+4)^3/2, lies in the z=0 plane for 0≤x≤2m and 0≤y≤2m.Determine E at (0,0,2)m Ans:(18x10^9)(-16/3ax-4ay+8az) Homework Equations E=kQ/R2 The Attempt at a Solution dE=ρdA / R^2 aR...

I want to calculate the correlation length of a rough surface from the intensity profile of diffuse and specular reflectance from that rough surface. By fitting with the Gaussian curve, I calculated FWHM of the intensity profile.Generally it is considered thatcorrelation length = 2/FWHMI also...

Homework Statement Say I have a detector that detects alpha-particles of some decay process. Let N be the amount of particles detected and let N be Poisson distributed. If I now define the intensity to be the amount of detected particles per second I = N/t, what would the standard deviation of...

Third question about wave optics in two days, hope it's not too much. When we look at the intensity of light on the screen in a double-slit interference experiment (assuming negligible diffraction), we find something like this : When we look at the intensity of light on screen in a...

Homework Statement Unpolarized light of intensitry 3 W/m^2 goes through two polarizing films. Their axes are 60 degrees apart. What is the intensity of light transimitted by the second film Homework Equations ##I_2 = I_1*cos^2 phi## Where I_1 is the intensity of light after going through the...

Hello forum, Is there any method of knowing the location of source and probably intensity of vibration from afar without sorting to a doppler effect? This is in the same as our auditory sense, when people call us at a distance we could easily approximate how far they are and the volume they speak

Homework Statement Monochromatic light of wavelength 463 nm from a distant source passes through a slit that is 0.0350 mm wide. In the resulting diffraction pattern, the intensity at the center of the central maximum (θ = 0∘) is 9.20*10-5W/m2 . What is the intensity at a point on the screen...

3 point charges q1 q2 & q3 are placed in vacuum as shown. Find electric field intensity at B,if q1=2C,q2=-4C & q3=-2C Homework EquationsThe Attempt at a Solution

I am not getting the answer to this question as shown in the textbook. Please help...! My attempt is in the last attachment. Thanks.!

Homework Statement Show that the electric field E outside a spherical shell of uniform charge density ρs is the same as due to the total charge on the shell located at the centre. Homework Equations Using only Coulomb's Law E=Q/4πε0 ar The Attempt at a Solution If i assumed it as circular...

I would appreciate if the explanation didn't derive this phenomenon using Malsus' Law exclusively and would go into the horizontal and vertical components of polarized light, and how the blocking of the horizontal components results in a halved intensity...so more of a geometric explanation...

Hello folks, Can anyone explain to me what is the difference between magnetic field intensity H and magnetic field density B?

Is the visible light on the surface of Pluto equivalent in intensity to what it is on Earth? That is, is 1 lux = 1 lux even though it takes light that much longer to get there from the sun? Or are images of distant objects in the solar system taken with longer exposures?

Homework Statement An enclosed chamber with sound absorbing walls has a 2.0 m × 1.0 m opening for an outside window. A loudspeaker is located outdoors, 46 m away and facing the window. The intensity level of the sound entering the window space from the loudspeaker is 42 dB. Assume the acoustic...

Hello, I only have 1 question left to finish my physics homework, and it has to do with sound and intensity. I am having some trouble figuring out how to solve it. Here is the question: At a distance of 17 km, a 177 Hz horn, assumed to be an isotropic point source, is barely audible. At what...

Homework Statement You have a light bulb where the filament (in vacuum space) starts to glow. This light hits the glass of the bulb at 90 degrees from distance R and is transmitted through the glass of thickness s into the air, of index of refraction nair. So light travels like this: vacuum...

Homework Statement We have a Star with known temperature T, Radius R and distance from us. 1) Say we know the effective temperature ##T_{eff}## and we want to calculate the intensity ##I(λ.T) at λ=5500 A##. 2) Suppose that ##I(λ,T)## is constant over the range of visual band and...

How can I compute the intensity of an electromagnetic radiation if I know ##e_x, e_y, e_z, h_x, h_y,## and ##h_z##, where ##e_i## is the electric field component at ##i## and ##h_i## is the magnetic field component, also at ##i##? Thank you in advance.

Homework Statement If you install special sound-reflecting windows that reduce the sound intensity level by 35.0 dB , by what factor have you reduced the sound intensity? Homework Equations Δβ=10Log(I/I°) The Attempt at a Solution I°=10^-12 I=I°-35 35=10^1.5440680...

Homework Statement How can I get the maximum Current Intensity by connecting 72 cells to a 3 Ohm resistor each cell has a potential difference of 1.5 Volt and internal resistance of 1 Ohm Please don't tell me to connect them all in parallel or all in series as in parallel the potential...

Homework Statement Brown coal, energy content 16 MJ/kg, carbon content 65% by weight, burning in a 30% efficient steam power plant. Homework Equations What is the emissions intensity (kg CO2 emitted/kWh delivered) ? Compare this to Hazelwood which is 1.53 tCO2/Mwh 3. The Attempt at a Solution...

I want a better visual model of what Newton's gravitational force formula represents: (G⋅m1⋅m2)/d2 But there are two contradictory things that I'm having trouble reconciling: Multiplying the two masses shows a relationship between the two point sources, but using the area of the sphere to...

I recently read about the recommended amount of exposure time to high sound volumes: http://www.dangerousdecibels.org/education/information-center/decibel-exposure-time-guidelines/. Since I am in the Band at school I was somewhat concerned about if the sound intensity would be too much...

Homework Statement Suppose you have a disk of radius r at x=y=z=0 with its normal pointing up along the z-axis. The disk radiates with specific intensity I(\theta) from its upper surface. Imagine the observer plane is at z=Z, where Z is much greater than r. Let I(\theta) = I = constant...

http://www.quora.com/Why-is-the-spectrum-of-Bremsstrahlung-radiation-continuous In the above link, it says that "you will count more low-energy events since they are more probable." Which must mean that at lower energy we must get more intense radiation...

Homework Statement Homework Equations dsinθ=nλ IαA2 The Attempt at a Solution I chose D because I thought that D gives the max intensity since the amplitudes superimpose over a smaller area. But the answer is C. I can't see why.

Okay, so I have completed a practical where I used a light box and then placed different coloured plastics in front of the light and measured the light intensity of each colour. From the results I found that yellow, orange and violet had the highest intensities, with red and green having the...

Homework Statement Fans at a stadium produce sound that is heard 1km away, the intensity level is 60 dB. How much acoustic power is generated by the fans? Homework Equations B = 10 log (I÷I_0) P=I*A The Attempt at a Solution I= 10^-12*6^10= 10^-6W/m^2 P= 10^-6*4pi*1000^2 =12.56W However...

For electromagnetic wave if it's reflected from a perfect conductor standing wave can be form. I wonder why Poynting vector can be used to describe the intensity of standing EM wave. (see p.19 of http://web.mit.edu/viz/EM/visualizations/coursenotes/modules/guide13.pdf ). From some textbooks...

Hello everyone, I am currently doing my masters research project on fracture mechanics. My problem is such that I have a flat circular disc(brittle) which is simply supported around its circumference. The top surface of the disc is subjected to a point load at its centre. the bottom surface has...

Please forgive me if I am posting in the wrong forum. Also the board limits the length of the title. I wanted to ask about Effect of high intensity electric and magnetic fields on gravity. To begin, 15 years ago this was published...

Homework Statement Plate capacitor with distance between plates 'd=4mm' is fully filled with homogeneous linear dielectric. Capacitor is connected to the source of DC voltage, first stationary state is established, then the capacitor is separated from DC voltage source. After that, dielectric...

Hello. I have some question about iridium flares. My brains can' t process the whole picture. Iridium panell works like a mirror and reflects quite some percantege of light to the Earth's surface, where it makes a bright spot with quite a big radeous. An observer sees a bright spot in the sky...

Homework Statement It's not a homework, I'm just studying for the exam, but one question that I'm not sure of the answer is: "In the semiclassical model of a two-level atom interacting with a monochromatic field, how does the Rabi frequency scale with the laser intensity" Homework Equations...