Intensity Definition and 898 Threads

Homework Statement Hello! This is really a simple question about how to use reflection and transmittance coefficients. I have a light ray of intensity I0 comming (S-polarized) to a glass surface at a certain angle, like in the picture: I want to find the intensity of the reflected...

Quantifying an "Off-axis" Neutrinos (probability and intensity) Considering the modelling of a high energy proton beam neutrino experiment. I have questions concerning the scattering of neutrinos from the axis of the proton beam. I understand that a muon beam (derived from a proton beam)...

Homework Statement An alarm clock makes a sound that has intensity 60 dB at a distance of 1 m. What is the sound intensity of 100 such clocks which are all 100m away? (A) 0.6 dB (B) 40 dB (C) 50 dB (D) 60 dB Homework Equations I1/I2 = R2^2/R1^2 The Attempt at a Solution If...

Homework Statement At 1 m away from the source of a sound, the intensity of the sound is 90 dB. At 10 m away the intensity is…? The answer is 70 dB but I don't know how... Homework Equations I = Power/Area The Attempt at a Solution My thought was to set up the equations...

A few months back my colleagues and I are facing a problem where the intensity of our sapphire peak fluctuates every time an XRD phase analysis was done, even when the scan was done on the same sample. By accident, I found that the orientation of the sapphire substrate with respect to phi...

Homework Statement Initially unpolarized light is shining on a series of six polarizers in a row. Each polarizer is rotated by the same angle, θ, relative to the previous polarizer. Choose a fraction (anything less than 1) as your final intensity. What is the angle, θ, such that the...

Homework Statement One wheel goes at 850 rpm and the other at 780 rpm, and obviously they make a noise. Standing in an enclosed room, you hear the sound intensity increase and then decrease periodically due to wave interference. How long does it take between successive times for the sound...

Can someone please explain why the are used is 4∏D2? Shouldn't it just be ∏r2?

Homework Statement A point source of sound emits energy equally in all directions at a constant rate and a person 8m from the source listens. After a while, the intensity of the source is halved. If the person wishes the sound to seem as loud as before, how far should he be now from the...

Homework Statement Two loudspeakers A and B of equal power are separated by a distance of 1.4 m. Both the speakers emit sound waves in phase and of frequency 450 Hz. If a microphone were to be moved from A in a direction perpendicular to AB, at what distances from A will it detect a minimum...

I'm a bit confused because the sun's radiation & heat are passing through space (with some passing through planets' atmospheres), and there is almost nothing in space, therefore, how does that immense heat & light just diminish over AU distances when its going through almost nothingness? What...

Homework Statement Infinite uniform line charges of 5nc/m lie along the (positive and negative) x and y axes in free space. Find E at :P(0,3,4) Homework Equations E due to line charge along the Z-axis is given by: E=(λ/(2∏*ε*r))*ar where λ=line charge density;ε=...

I know that this question may sound silly , but I really can't get the difference between intensity and density in general ! And the whole magnetic field thing makes it worse , in my textbook , its written that magnetic field intensity is the same as magnetic flux density , but no matter how...

Homework Statement A beam of polarized light is sent through a system of two polarizing sheets. Relative to the polarization direction of that incident light, the polarizing directions of the sheets are at angles θ for the first sheet and 90° for the second sheet. If 0.10 of the incident...

Homework Statement Two infinitely long filaments are placed parallel to the x-axis as shown in Figure 1. a)Find H at the origin b)Find H at (-1,2,2) Homework Equations ∫Hdl=Ienclosed H=H1+H2 The Attempt at a Solution Well following the equation above I get Hl= Ienc then...

I have just completed an experiment on principles of lasing, constructing a laser and measuring the beams intensity distribution. This distribution of the beam was measured using a detector mounted on a traveling microscope. The detector had a pinhole cover such that only a small fraction of the...

Homework Statement I need to derive the intensity distribution of the double slit experiment. Intensity as a function of the slit separation d, the distance to the screen L and the wavelength \lambda. L>>d Homework Equations The Attempt at a Solution Ok this is ridiculous but...

According to my prof, increasing intensity of the light source in a photocell for the photoelectric effect does not increase the kinetic energy of photoelectrons emitted. Instead, the number of electrons emitted (and current) increases. Changing the colour of the light causes an increase in...

A reading from e=mc2 by David Bodanis, The big question though is why? Why is squaring the velocity of what you measure such an accurate way to describe what happens in nature? One reason is that the very geometry of our world often produces squared numbers. When you move twice as close...

This is something I don't relly get. I keep reading that the intensity of a wave is proportional to the square of its amplitude. So let's suppose we have a random wave source, with amplitude A0. If we replace that source with five identical copies of it, their collective amplitude is 5A, yes...

This is something I don't relly get. I keep reading that the intensity of a wave is proportional to the square of its amplitude. So let's suppose we have a random wave source, with amplitude A0. If we replace that source with five identical copies of it, their collective amplitude is 5A, yes...

We know that the intensity of the light in the light bulb depends on the electric current. And I want to know who was the first physicist who proved this. And if there is a possibility could you also tell me how, why, when, where he did this experiment or give me an website, but the name of...

Hi guys, let's say we have a wave where the power P is proportionate to the square of its amplitude, which is A^2. If now we have 2 identical waves in superposition in phase, then we have an amplitude of 2A am i right? Next, we realize that because of the amplitude of the superposed waves is...

Here's a question I got on an exam: During a typical workday (eight hours), the average sound intensity arriving at Larry's ear is 1.8 x 10-5 W/m2. If the area of Larry's ear through which the sound passes is 2.1 10-3 m2, what is the total energy entering each of Larry's ears during the...

Good afternoon all My question is, when we observe stationary waves, and we know that at a certain point, the sound is maximum, is this the displacement node or the displacement antinode? I have read a few different sources and currently i have encountered both. To me it makes more sense...

Hello all, I'm a new Mechanical engineering graduate student who needs help using a photodiode. I'd like to rig up some kind of circuit that will let me measure the intensity of laser light. This is kind of a new area for me haven't really done anything like this before so forgive me if I come...

What is the equation to find relative sound intensity from a source when given the angle?

Hello, I am currently working on a problem to calculate the light that makes it through a half circle. For example, say I put a cylinder out in the sun, where the intensity is known to be 1030 W/m^2. I would like to compute the intensity/energy/power that makes it into this. Now, given the...

Homework Statement A beam of unpolarized light is incident on a series of three polarizers as shown. The angle of the transmission axis of each polarizer is indicated by the dashed line, with q1 = 110, q2 =230, and q3 = 370 (all defined relative to vertical). What is the ratio of the...

Homework Statement In order to decrease the intensity of a beam of unpolarized light to 10% of its original intensity using two polarizers, what is the required value of θ, the angle between the transmission axes of the two polarizers? Homework Equations tanθB=n2/n1 The...

Hi everyone here, hope you enjoying this summer .. i'm taking ' elements of electromagnetic ' course this summer session and i just have a little question here in the yellow shaded statement shouldn't it be dl = (l/N) dz instead of dl=(N/l) dz ? By the way, it's not a HW...

A +7.5 nC point charge and a -2.0 point charge are 3.0 cm apart. What is the electric field strength at the midpoint between the two charges? just give me the formula ?

Hi, https://www.physicsforums.com/attachment.php?attachmentid=60066&stc=1&d=1372909704 I would like to ask a question on thermal radiation. In the attached image, if all three surfaces \{ dA,d{S_1},d{S_2}\} are black body surface, and d{S_2} = d{S_1} = S, then does d{S_2} receive the same...

I'm having difficulty understanding the solution to this question. "A source creates a sound that is observed at 200 Watts per meter squared. If the intensity level of the observed sound decreases by 20 decibels what is the decrease in observed intensity? The way I solved it was I saw 20...

Homework Statement Question: Calculate the wavelength in mm of the most intensive microwaves Question before: State the intensity of the most intensive microwaves detected Answer: 380 Units. (5 Waves per CM) [Read from a graph] Homework Equations None given. The Attempt at a Solution I...

Homework Statement 1.An unpolarized beam of light is incident on a stack of four ideal polarizing filters. Each of the second, third and fourth polarizers is rotated by 30.0o relative to the preceding polarizer. In this way, the axis of the first polarizer is perpendicular to the axis of the...

Describe the pattern of intensity vs wavelength observed in blackbody experiments and explain why these observations were in conflict with the predictions of classical physics. is this right? the shorter the wavelength, the greater the intensity. This is wht I wrote: Classical...

The electric intensity E, current density j and specific resistance k are related to each other by the relation please explain

I was working on an image processing project a while ago and was specifically working with raster images in the Hue-Saturation-Value(HSV) image format. Each is determined by mathematical values of these (HSV) parameters. I also worked with other bases such as the Red Blue Green (RGB) format. Now...

If energy is kept constant and intensity of photons is increased, will the threshold frequency be lowered? I ask because I'd like to understand this graph - http://www.flickr.com/photos/coachrobbo/3909285882/ "lower intensity same frequency" causes stopping voltage to be lowered, thus...

Homework Statement If Phrank's new speakers produce a sound of 90dB at 10m, a) How many decibels would be required for the sound to be one hundred times the intensity? b) How close would Phrank need to stand for the intensity to be at 60dB? Homework Equations β2 - β1 = 10 log...

hello I amm trying to understand the difference between flux and specific intensity of radiation. I understand that one is dependent on distance the other is not, but can you make it more tangible with an example?

Hi all, What is the relation between RAMAN Intensity and Energy of the photon and/or bond stregth and/or bond energy? Is there any equation or sth explain it easily? If you can explain it in a simple way, I will appreciate. Thanks

Homework Statement Please refer to the image. Question (a). Homework Equations I= P/(4∏r^2) P=E/t The Attempt at a Solution After a few attempts, I found the way to get the answer: (6.3 x 10^-6) x (1.5 x 10^-4) x 60 = 5.67 x 10^-8 But I don't understand why the area of...

I am really confused about this! So people thought that as wavelength increases for electromagnetic radiation, intensity of radiation increases but this would mean that people would melt if exposed to any radiation higher than visible light. But then they did an experiment and they sketched the...

Hello, Is there an established relationship between the diffraction intensity that a sample produces with its band structure? Thanks

The problem: You and your engineering crew are in charge of setting up a wireless telephone network for a village in a mountainous region. The transmitting antenna of one station is an electric dipole antenna located atop a mountain 2.00 km above sea level. There is a nearby mountain that is...

Homework Statement Homework Equations The Attempt at a Solution For the second part, I got an answer that is indpendent of the index of oil? That woud mean that the answer would be the same as putting it directly through water.. No clue about the third part. For the last part, Not sure...

Hi, I am not a physicists and have been trying to understand some basic concepts about electromagnetic waves in the context of telecommunications. Now, this is what I know so far: the energy of electromagnetic waves is proportional to it's frequency (E = h*f), and basically it's the energy...

Howdy everyone. 1. Ok, so we have and electromagnetic wave propagating through a vacuum. We know wavelength, and the magnitudes of B in the x and y directions. Also, B=[Bx(i)+By(j)]cos(kz+ωt). That's all the prereq stuff. 2. So Intensity is: <P>/A & (1/2)Bmax^2/Zo I'm def feeling...