Pulse Definition and 323 Threads

Homework Statement A certain type of laser emits light that has a frequency of 5.1* 10^14 Hz. The light, however, occurs as a series of short pulses, each lasting for a time of 2.6* 10^-11 s. (a) How many wavelengths are there in one pulse? (b) The light enters a pool of water. The frequency...

I am interested in looking at the voltage component of a short (possibly nanosecond width) pulse in a coaxial cable along the cable at a given distance, Z, along the line. I am "cheating" by using the steady state Telegrapher's equation [Eq. 1] and formulating a periodic pulse approximation. It...

Homework Statement "A 1 fs pulse of laser light would be 0.3 um long. What is the range of wavelengths in a 0.3 um long pulse of (approximately) 600nm laser light?" Homework Equations (delta omega)(delta t) >= 1/2 c = (lambda)(frequency) The Attempt at a Solution I replaced (delta...

how can i "pulse" a DC current at a rate of Ghz i need to pulse a dc current through a circuit in at 2.45Ghz. astable multivibrator style How might i go about doing this

Maybe a stupid question, but anyway. The paper "Experimental Quantum Cryptography" by C. Bennettet al. discusses laser pulses of 0.1 expected photon per pulse. What does that mean physically? Is it that 90% of laser pulses are not pulses at all, containing no photons and thereby no energy? Or...

Hi, I am wondering if it is possible to generate voltage pulses (square or sinuosoidal, +/- 5V) using a computer. If yes, then how would I go about doing it? Thanks.

Homework Statement Pulsed lasers used for science and medicine produce very brief bursts of electromagnetic energy. If the laser light wavelength is 532 nm, and the pulse lasts for 37 ps, (a) how many wavelengths are found within the laser pulse? (b) How brief would the pulse need to be to...

Hello Everyone, I am working on a system for an undergraduate project that uses pulse width modulation to power two electromagnetic clutches. I have a pic microcontroller that is supplying a PWM signal to a MOSFET that is in turn switching the ground side of my clutches. Everything seems...

This is my first post, so a little background on me: I am a senior in EE at UofL, I am currently working for a company who has given me a larger project to complete (They kept me on part time while I finish school). I have not taken any analog or digital design classes, so I fear I am in over...

Time standards are now based on atomic clocks. A promising second standard is based on pulsars, which are rotating neutron stars (highly compact stars consisting only of neutrons). Some rotate at a rate that is highly stable, sending out a radio beacon that sweeps briefly across Earth once with...

A smaller ”boom” I'm currently writing a science fiction novel, and while I'm certainly no physicist, I still aim to minimize the use of handwave devices built from unobtainium. It appears that the only propulsion system realizable with technology in use today or in the near future which...

Homework Statement A wave pulse is described by the function y(x,t)=De^-(Bx-Ct)^2, where B, C and D are all positive constants. What is the speed of this wave? Homework Equations y=f(x+vt) The Attempt at a Solution y=De^-(Bx-Ct)^2 is of the form y=f(x+vt) however there is a B in...

A pulse jet has only one moving part. Nice. But what if it didn't need any moving parts? Stupid idea, right? Check out this stupid idea. They're all over the internet. http://www.youtube.com/watch?v=5U-grFuXZ9U&feature=related"

Hey guys, I'm sure I'm doing something really daft in not getting this to work, but... I want to use NDSolve to numerically solve the time evolution of a (one-dimensional) wave pulse in either the time dependent schrodinger or KG equations. My inability to do so stems from my lack of...

Homework Statement In Fig a line is used to produce a short rectangular pulse of width 12ns and peak value 800V. With S-2 open. S-1 is closed to charge the line to Vdc; after charging, S-1 is opened. Then, at t = 0, S-2 is closed to discharge the line through RR and form the pulse. Find the...

Dear All, I am making a MIDI Drum project. I want to convert the pressure sensed by piezo into pulse width with presetable setting to shift the offset level above which the output pulse will be generated. If you have any other idea to convert pressure to pulse width kindly let me know...

Hi, can anyone explain how to tune the pulse width of excimer laser? Thanks Baris

Pulse of neutrinos, E>>m, hits plasma-->charge seperation? When a large pulse of neutrinos, each with an energy much greater than the electron rest mass energy, hits some plasma does this give rise to charge separation for the plasma? Could one make a simple argument why this is true or false...

Is this method good for analyzing a pulse? Why is the averaging of the spectra good for noise cleaning? What's the criteria for defining how much windows in a set of data one should take? Anyone who clarifies this has a big thanks from me.

Hi, What is the equation for a E field of a single pulse of a laser? If that laser is shined onto say a grating spectroscope (square law detector), how can I go about deriving an expression for Intensity as a function of frequency at the output of the spectroscope? I know that the square...

I believe that the path of the photons will bend towards the center of mass, but I wonder what happens to the wavelength and the pulse shape while the photons are in the gravity well. The photons don't undergo any real acceleration, since they are in free fall, so their wavelengths should...

Homework Statement The NIF will use extremely powerful lasers to attempt to implode a D-T target and thus initiate nuclear fusion. One pulse of the lasers will only last for 1 nanosecond, but the total energy is expected to hit 1.8 megajoules. The wavelength is in the near ultraviolet, 350 nm...

Hi, this is the question: For part a) I did V=(L/C)-1/2=2.5x108 m/s. And then I said T=x/v where x=10m, so T=4x10-8s. For part b) V++V-=VL...since it's the first wave I suppose there wouldn't be a reflecting wave yet, so V-=0. I have an equation that says V+=[VL/2](1+R0/RL)...since...

I would like to know the difference between pulse response and impulse response. I looked for "pulse" and "impulse" on the internet and found that on some websites they had been used interchangeably. Apart from that I checked out some books and found that they use the term "impulse response"...

Homework Statement A light pulse is emitted in an inertial frame. You are moving at a constant velocity of c AWAY from the pulse, and initially 10m away from the pulse. Will the pulse reach you, and what velocity will you measure for c? Homework Equations The Attempt at a...

Hi, I would like to ask if anyone with VFD and PWM - Invertor knowledge could give me a run down on the advantages of a 36 Pulse VFD Unit in comparison to a 12 Pulse? Is the cancellation of harmonics a factor in Pulse selection? Thankyou C

Since a string pulse get amplified when it enters a less dense medium such as from the thick heavy rope to a lighter string, why does not light do the same?

Is that an official theory or just a light/naive guess (maybe mine)that, if after big bang everything expands, and we can be pretty sure every galactic center is a massive black hole -than galactics are"joining forces" to make it all(universe) back to the point the big bang happens again(and...

Hi, everyone. Can someone help me to understand pulse? What is the meaning of temporal shape? is it means the intensity distribution of the pulse is following the shape? What is the relationship between temporal shape and spectral mode distribution? Is that the Fourier transform...

At my business we are beginning the design of gas detection systems using IR. My question is what are the benefits of operating solid state IR sources in a pulsed mode?

Suppose the earth, moon, and an extraterrestial observer(ET) are at the corner of an equilateral triangle. The Earth observer points a laser at the moon and emits a powerful laser pulse for exactly .01 seconds. The 1,860 mile long pulse travels to the moon in about 1.3 seconds. The ET knows that...

Homework Statement A string of length l = 5 m weighs M = 10 kg . A pulse wave is traveling along the string. What is the speed v of the crest of the pulse, in the uint of m/s , if the tension of the string F is 200 N ? Homework Equations v= sqrt F/u u= m/L HELP: We can...

Homework Statement A very short pulse UV laser is used to liberate a number of electrons from the negative plate in the arrangement in (i) above. The electrons drift towards the positive plate under the influence of the electric field over a time scale much longer than the laser pulse...

Hi, Energy density of the ith annular section of a Gaussian pulse is written as F(r_i, r_i+1)=2*totalEnergy/[(r_i+1^2-r_i^2)*w^2]*integral(r*exp(-r^2/w^2),from r_i to r_i+1) where r spans from r=0 to r=r_n (theoretically infinity) in n steps, w is the waist size of the beam. This...

I`ve had a new idea in designing a pulse jet by adding a valve in it... According to my intuition and logically this increases the output many folds and I`ve given sufficient reasons for suggesting it. I have a powerpoint of my idea that I have made and I request any of you to please go through...

hello i have been having trouble working with bipolar transistor. i have been taking pulses that at less then 1us long and amplifying them with transistors. how ever if i have a bipolar transistor as part of my amplifier whether it is my inputs are as part of another stage the pulses always are...

Well I want to understand the internal working off the valveless pulse jet, I have red something but everything is qualitative, I would like to ask to you if you know some book describing every process off this kind of engines mathly, including the kadenacy effect. You have a lot of physics...

Hello, new kid on the block here. I have read the rules and hereby present my question. My aim is to calculate the period of a transient DC magnetic field from a half sine wave magnetiser output into an air core wirewound coil. Coil Resistance : 14.66 mili ohms (derived using voltage drop...

help me out with circuit diagram of pulse generator with varying pulse width,amplitude and frequency

Hi, I'm trying to build a high frequency generator. The pulse needs to have atleast 1ns rise/fall time, variable amplitude (~0-8V), 50 Ohm output impedance, and have very little jitter/be stable and I need to be able to set the pulse width and delay from ~5-1000ns. Cheers, Steve

If you were to design a pulse jet engine where would you start? How do you determine the diameter and length of the tail pipe? How do you determine the diameter and length of the combustion chamber? How do you determine the area of the air intake valve system? How do you determine...

Please suggest a method to generate a 1ns pulse. with 680MHz frequency. i.e ton: 1ns. the pin should also be able to generate pulses with pulse width anything from 1ns to 4s with 1ns step, i.e the pulse can take any value b/n 1 ns and 4s with 1ns step. This pulse is used to trigger a laser...

Does anyone know any Forumulas or how to calculate the dimensions of a pulse jet engine? I have already built several PULSE JET engines that run by scaling up an existing hobby engine to a larger size. Problem is the scaled up models run but maybe they could run better. I can not find any...

I'm new to the forum, so hello! How can i calculate the magnetic field strength of the pulse of an air core coil, the number of turns is 20 & the height of the coil is 20mm, not single or multi layered just random wound. The pulse is 10V & 1Amp, the Inductance is 200uH. Not sure how to go...

Homework Statement F(w) is the Fourier transform of f(t). Write down the equation for F(w) in terms of f(t). A rectangular pulse has height H and total length t0 in time. Show that as a function of w, the amplitude density is propertional to sinc(wt0/2). Homework Equations F(w) =...

http://i662.photobucket.com/albums/uu347/TwinGemini14/showme3.gif The top picture to the right is the picture of the rope before the wave pulse arrives, and the bottom picture to the right is a picture of the rope after the wave pulse has arrived. Notice that the rope has to stretch in...

I want to use a pulse current instead of continuous current in the Laser rate equation as input. What would be the equation for the Gaussian expression when I'll swap the continuous current with pulsed current in my equation and implement it in Matlab? please let me know the ans if u have any

A pulse 300ns long is made using a continuous wave laser and a very(very) fast shutter. What is (approx.) the minimum spectral width of the pulse? I have no idea where to start. For starters what is the spectral width? and how would i go about solving this problem. Not looking for a...

We have been asked to make any circuit of our choice using op-amps on a breadboard or a PCB. We have found this circuit of PULSE WIDTH MODULATOR on the net and we have decided to go for it.But our teacher wants us to explain the designing of the circuit too namely why have we used the resiistors...

I need to make a pulse of varing length. Either I need a VCR/VDR to control the length of a momo stable pules, or a VCO to trigger a preset monostable at different times. I have been trying to find some thing to do the job for me but havn't had any luck. The VCR2N/4N/7N made by Siliconix are...