Intensity Definition and 898 Threads

Sound Intensity "pig calling contest" In a pig-calling contest, a caller produces a sound with an intensity level of 110db. How many such callers would be required to reach the pain level of 120db? The equation I think I have to use is (db_1 - db_2)=10*log(power_1 / power_2) The...

Homework Statement https://tycho-s.phys.washington.edu/cgi/courses/shell/common/showme.pl?courses/phys123/spring08/homework/01b/twospeaker_INT/02.05.gif (if image doesn't show up...it is a right angle triangle with S1 at the right angle, 4m between it and O and 3m between S1 and S2) The...

1. Consider N similar antennas emitting linearly polarized electromagnetic radiation of wavelength \lambda and velocity c. The antennas are located along the x-axis at a separation \lambda form each other. An observer is located on the x-axis at a great distance from the antennas. When a single...

Hi Guys, I am new to this forum and have a "quick" question. Say you had a laser pointer and you directed the laser through a glass block and then to a LDR why would the light intensity recorded be lower than without the glass block? What is happening to the light when it is in the glass...

Can anyone explain how to go from: I_s = \frac{nc\epsilon}{2} |E|^2 to I_s = \frac{nc}{8\pi} |E|^2 That means \epsilon is \frac{1}{4\pi} ...I can't find that anywhere.

Homework Statement Electromagnetic radiation of wavelength λ and Intensity I, when incident on a metal surface, causes n electrons to be ejected per unit time. The maximum kinetic energy of the electrons is Emax. State and explain the effect, if any on n and Emax when the wavelength λ is...

"If two flutists play ther instuments together at the same intensity, is the sound twice as loud as that of either flutist playing alone at the intensity? Why or why not?" I know that the answer has something to do with the sensation of loudness being logarithmic in the human ear, but I...

Homework Statement A person standing a certain distance from an airplane with four equally noisy jet engines is feeling a sound level intensity bordering on pain, 114 dB. What sound level intensity would this person experience if the captain shut down all but one engine? I have no idea...

[SOLVED] Sound Intensity Please help! Homework Statement The sound intensity level 5.0m from a point source is 95 dB. At what distance will it be 75 dB? Homework Equations dB = 10log(I/Io) I = P/4*pi*r^2 The Attempt at a Solution I honestly don't know what to do with this...

Direction of field intensity...? Problem: "The vector that best describes the direction of the electric field intensity at point x on the 200Volt equipotential line is"?... ...(five multiple choice options) There is a diagram of decreasing/increasing equipotentail lines with a point "x" on...

This is the question Find the intensity of a light source that produces an illumination of 7.50 lux at a distance of 30m from the source. This what I get but it's wrong 84823 This is the formula E = Illumination I = luminous intensity of the source ( in lumens) r= distance...

Homework Statement The intensity at a distance of 6.0m from a source that is radiating equally in all directions is 6.0x10^-10 W/m^2. What is the power emitted by the source? They give you multiple choice answers, and the answer is 2.7x10-7 W. Homework Equations I is...

Is it possible to have a negative sound intensity level? A sound that is below the threshold of human hearing has... (A) a negative intensity level (in dB). (B) a negative intensity (in W/m^2 ). (C) an intensity level of zero. (D)an intensity level less than 1 dB , but greater than 0...

I am in eleventh standard , In my book it is given about the plane progressive simple harmonic wave , later somewhere is mentioned about intensity of wave what my doubt is intensity is defined as energy/area but what about waves in 2d or 1d plane SHW are 1d as wave progresses in x-axis...

Homework Statement A low energy, 13-watt bulb illuminates your desk from a distance of 1.2m. You can assume that it acts as a point source and that it is 100% efficient. What is the intensity (power per unit area) at the desk (in Wmˉ²)? Homework Equations Velocity = Frequency * Wavelength...

Homework Statement A concert loudspeaker suspended high off the ground emits 28.0W of sound power. A small microphone with a 0.900cm^2 area is 51.0m from the speaker. A) What is I at the microphone? B) How much sound energy impinges on the microphone in J? Homework Equations I = P/A I =...

Homework Statement Two identical stars have intensity readings in a 40 to 1 ratio. Calculate the ratio of their distances. Two similar lights are at distances in a ratio of 8 to 785. Calculate the ratio of intensities. All I want to know is if I use E1D1^2=E2D2^2 or I1/D1^2=I2/D2^2...

Homework Statement We will make a Spin-Echo experiment, and we know \rho_{w}, T1_{w},T2_{w}, \rho_{g},T1_{g},T2_{g}, where T1 and T2 are relaxation time,\rho is a proton density, and g mean gray matter, w mean white matter. We search TR and TE, TR is a repetition time, TE is an echo time. We...

Homework Statement During a rehearsal, all eight members of the first violin section of an orchestra play a very soft passage. The sound intensity level at a certain point in the concert hall is 32.0 dB. What is the sound intensity level at the same point if only one of the violinists plays...

Homework Statement The sound level 24 m from a loudspeaker is 66 dB. What is the rate at which sound energy is produced by the loudspeaker, assuming it to be an isotropic source? ____W Homework Equations ? Something to do with Intensity? The Attempt at a Solution I don't...

Homework Statement You are the captain of a submarine that is on a secret mission deep inside enemy waters. Suddenly your ship is “pinged” by another sub. You are able to determine that the ping comes from the North, has an intensity level of 86.4 dB, and has a frequency of 7270 Hz. You know...

Homework Statement Michelle is enjoying a picnic across the valley from a cliff. She is playing music on her radio (assume it to be an isotropic source) and notices an echo from the cliff. She claps her hands and the echo takes 1.2 s to return. (a) Given that the speed of sound in air is 343...

I am struggling with understanding the difference between decibels and intensity. I know that intensity can be measure in decibels but they are not always the same thing. I have a problem where there is a police car 200 meters from an accident runing sirens at 80 decibels. I am asked to find...

Homework Statement You're in an airplan whose two engines are running at 560rpm and 570 rpm. How often do you hear the sound intesity increase as a result of wave interference? Well, i know that the intensity will increase when the wave interference is constructive, but point me in the...

A sound wave has a frequency of 1665 Hz and a pressure amplitude of 1.13 x 10^-3 Pa. What were (a) the displacement amplitude and (b) the intensity of the wave emitted by the ear? the equation i used for a is sm=delta(pm)/(vpw) where p is the density, sm is the displacement amplitude, pm...

Homework Statement The intensity of sunlight that reaches the Earth's atmosphere is about 1500 W/m2. What is the intensity of the sunlight that reaches Jupiter? Jupiter is 5.4 times as far from the sun as Earth. [Hint: Treat the Sun as an isotropic source of light waves.] ____ W/m2...

[SOLVED] Help with a Wave Intensity Problem Hello all, here is a problem that relates to Wave Motion, more specifically Wave Intensity I believe: The figure shows two observers 20m apart on a line that connects them and a spherical light source. Figure: (The best I know to do) (Person...

Homework Statement There is evidence that elephants communicate via infrasound, generating rumbling vocalizations as low as 14hz that can travel up to 10km. The intensity level of these sounds can reach 103dB, measured a distance of 5.0m from the source. Deteremine the intensity level of...

Homework Statement A hearing aid increases the sound intensity level, thereby allowing a person to hear better. For the following decibel increases, by how much does the intensity of sound increase? a)30dB b) 22dB Homework Equations \beta=10log (I/Io)The Attempt at a Solution I substitute...

Homework Statement A point-like source of electromagnetic waves radiates power uniformly in all directions at a single frequency. At a distance of 5.6 km from the source, a detector measures the intensity (energy flux density) of the wave to be 35.1 μW/m2 (microwatts per square meter)...

According to the text, at a distance of 50 m from a jet engine, the sound intensity is 10 W/m2. This corresponds to a loudness (or an intensity level) of 130 dB. [You should convince yourself that this is true.] If you find the sound too loud and you want to reduce the intensity by a factor of...

What do we mean in mathematical terms intensity of light at this point is I and when we say Power of light is P

Homework Statement An AM radio station broadcasts with a power of 21.0 kW at a frequency of 910 kHz. Estimate the intensity of the radio wave at a point 18.0 km from the broadcast antenna. Homework Equations I= p/A I1/I2=r2^2/r1^2 w=2pi f The Attempt at a Solution From the...

Help please! Here is the prob and i don't not know where or how to begin. 1.Jose was having a really bad day out on the bike. He should have checked the forecast. First, the wind coming out of nowhere. Must have been a steady 30 mph with gusts up to 50, head on. Then the lightning. First 1...

I have been given this question: What is the sound intensity 2 metres from a speaker which is producing a sound at 100 watts of power? I know the equation is I=P/A but i don't know if "A" stands for amplitude or area. Some books/sites say amplitude and some say area. But if it is area...I...

Hi all. A very simple question: what is the difference between sound pressure level and sound intensity level? It seems to me that sound presssure level also measure the "energy" since it is p^2, which shall be related to energy... If it is so, it seems that sound pressure level shall be the...

Hi peeps, i am having a project and i wish to clear some concept. 1. The shorter the wave length the higher the photon energy? Am i right? 2. The higher the intensity of light, the higher amount of photons exist in the light? Am i right? 3. So higher intensity plus short wave length...

A laser pulse has a duration of 50 fs (50E-15 s) and an energy of 1 mJ. The laser is focused to an area of 50 micrometers square. What is the peak intensity and peak electric field at the focus? I previously tried to do this problem with normal intensity equations using intensity =...

Hi all, i am relative new here and i have an enquiry which i really wish to see if anyone can help me out with this. From my understanding, photovoltaic cell works by using photons from light to generate eletricity. From what i know is that the lower the wavelength of light, the higher is the...

I am having fundamental difficulty in feeling the definition of specific intensity of a radiation field... questions: 1) Define a radiation field as precisely as possible. 2) Specific intensity defined at a point should remain the same whichever way we choose for the differential surface...

1. Homework Statement : Consider two lasers, one blue and one red. Which of the two lasers has the higher intensity? 2. these are my choices: The blue one. Cannot be decided based on the information given. The red one. 3. The Attempt at a Solution : The difference between these...

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 be seem as loud as before, how far should he be now...

Homework Statement A small source of sound radiates energy equally in all directions. At a particular frequency, the intensity of the sound 1.0 m from the source is 1.0 x 10-5m Wm-2, corresponding to an amplitude of oscillation of air molecules of 70milimetre. (Assume no energy loss) Find...

What causes the feedback (a noise increasing in intensity and pitch) sometimes heard when people speak through microphones? I'm sure I have enough background to understand an explanation, I've just never thought about it before.

Homework Statement A person is a certain distance away from a plane with three equally noisy engines at 120 dB. What is the sound intensity if two of the engines are shut off? Homework Equations B (in dB) = log I/Io The Attempt at a Solution using this equation: 120 dB = 10 log...

Intensity of light constant..why rate of emission of electrons changes?? Intensity of light constant..why rate of emission of electrons changes as frequency of the incident light increased??... is the rate increase or decrease?? help me.. thanks..

Please check to see if my solution is correct: Question: If a light source were increased by a factor of 2 in intensity, what would happen to the value of KE_max of each photoelectron? My solution: KE_max would stay the same because increasing the intesity by a factor of two would only...

Intensity of Light-- What factors contribute? What factors affect the intensity of light? What is intensity? Are the relationships or equations that link the intensity of light to other variables? I'm asking this because I'm not quite understanding intensity vs. frequency. I'm studying the...

Hi folks. I have read in several papers that the electric field intensity adjacent to the very tip of an electrode (the "point" in a point-plane geometry) surrounded by a dielectric medium is given by 2V / [r ln(4d/r)] where r is the tip radius, d is the point-plane spacing, and V is...

Hey! Im quite confused about spherical waves. I mean, I understand that a spherical wave can be described by \Psi = \frac{1}{r} e^{i r}, because the intensity of such a wave decreases as 1/r^2. The intensity of such a wave is given by I = 1/r^2 which makes sense to me. But a...