Carrier Definition and 127 Threads

If ##\psi(x, t)=\left(\frac{1}{2 \pi \alpha^{2}}\right)^{1 / 4} \frac{1}{\sqrt{\gamma}} e^{i p_{0}\left(x-p_{0} t / 2 m\right) / \hbar} e^{-\left(x-p_{0} t / m\right)^{2} / 4 \alpha^{2} \gamma}##where * ##\gamma=1+\frac{i t} {\tau}##( a complex number) * ##\tau=\frac{m h}{2...

Suppose I have a perfect crystal(e.g.TiO2-Rutile, band gap=3ev), under UV light, there should photoconductivity, according to the condensed matter theory, some of these excited conduction band electrons would form small polarons, I am wondering how many percent of the free conduction band...

Hello everyone, I'm trying to find the Voltage Carrier Signal and Voltage Modulating Signal from the power spectrum of a AM signal 1) I change the scale dBW to W and I have this: From this I have that Pc (Power of the Carrier signal) is 50 W and I don't know how to continue with the...

I saw this photo at CNN.com today, and I'm trying to figure out what the function could be for what looks like a linear antenna array lining both sides of the aircraft ski-jump launching ramp. They look to be an array of about 10m verticals along each side of the bow, but with the base of some...

Question: For frequency shift key modulation in the binary case, how are the two carrier frequencies chosen? From online reading, I have seen that the carriers are chosen to be different but also with the goal of minimising bandwidth and without any overlaps of the spectra, etc. However, I...

Suppose you have a non-uniformly doped piece of semiconductor (without an applied bias) such that the acceptor dopant concentration Na(x) decreases from left to right (as x increases). In this case, the equilibrium hole distribution p(x) will not be uniform since then there would be a net drift...

I was reading this news https://www.thedailybeast.com/navy-to-fire-captain-brett-crozier-of-virus-stricken-uss-theodore-roosevelt-who-begged-for-coronavirus-help As I'm far from good when it comes to understand english terms... what do they mean by fired? Does it mean just that he is no longer...

Is the carrier wave modulated or in other words "modified" with the information signal? If so how exactly is this done? I can't find or maybe I am looking at the wrong things but I don't understand how this is done. I know that AM is modulated with the amplitude and FM is modulated by the...

Is there a rule of thumb that once a semiconductor's intrinsic carrier density reaches 10^15 cm^-3, that the semiconductor cannot effectively be used to perform useful operations?

Hello: I have small question , as I read about the ATF research in the news ,a question present it self , why no one does any research on heat carrier in nuclear reactor that can absorb nuclear radiation and change it to infra red radiation ? Best H

*This is an introductory physics class for non-math majors. A typical jet fighter launched from an aircraft carrier reaches a take-off speed of 175mph over a distance of 310 ft. assuming the acceleration is constant, what is the jet's acceleration in (meters per second)? 2) how long does i...

If a carrier signal is 1000 Hz, and my message signal has a bandwidth of 100 Hz. Is there any change in frequency of the modulated signal? Why is it said that the message signal is now operating between 1000hz +/- 100Hz? I thought the original message signal frequency remains unchanged...

Many times, the charge carrier density of a material is determined from a Hall effect experiment, from ##R_H=1/(ne)## (SI units). Where ##R_H## is determined from a measured voltage and other controllable parameters. As far as I know, this simple formula comes from the obsolete Drude's model...

Homework Statement For silicon at T=300K with donor density ND=2×109cm−3, acceptor density NA=0 and ni=8.2×109cm−3, calculate the equilibrium electron and hole concentration Homework Equations n_0=\frac{N_D-N_A}{2}+\sqrt{\frac{N_D-N_A}{2}^2+n_i^2} p_o=\frac{n_i^2}{n_0} The Attempt at a...

If you created the following double slit experiment would you still see interference? 1) Modify the slits so that the path from photon source through one of the slits to the detector is much shorter than the path through the other slit. 2) put a shutter in front of the photon source so that you...

Is the failure to remove the carrier frequencies the problem with the audio output in the following videos?

Homework Statement A sample of Si at room temperature is doped with acceptors at a concentration of 3E16 cm^-3. An excess electron hole pair density of 1E14 cm^-3 is generated at some time t = 0. At t = 13.9 μs the excess EHP density is measured and found to be 5E13 cm^-3.(A). Does the initial...

<<<Moved from another forum. No template. >>> I have to solve this mechanical Problem... I solved it, but I get fpór By=0,448F (see at my calculation!) and the right answer is 0,3F...what did I wrong? I should solve A B C! B is a two-piece carrier. F and a is given!

Hi, I start at 100 MHz have 10 carrier frequencies all starting in phase at t=0 and the carrier frequencies have 25 kHz spacing. So my frequency range is 100-100.25 MHz, with 10 single frequencies equally spaced in this range. They are therefore all different frequencies, spaced 25khz apart...

Homework Statement I've looked up the intrinsic carrier concentration of silicon, and what I've got isn't close. The question says given there are ##2\times 10^{22}## electrons per cubic cm in silicon, and the bandgap is ##1.1##eV, what is the free electron concentration at room temperature...

Hi guys. I want to make a question about what kind of job can a physicist do. Excluding the academic carrier and the research, which kind of job can a physicist do? It is true that there are physicist that work at Wall Street? If yes, what kind of job they do there? A technical job? I don't...

I have a baseband signal in IQ form. I have a method to calculate the carrier offset and estimate the carrier bin. I want to center the carrier to the middle of the bandwidth. How do I do so? Do I simply multiply the IQ data by the exponential with the carrier offset, but doesn't that shift the...

I seem to have a lot of trouble understanding radio carrier signals I have read a bunch of stuff online and seen videos trying to explain it but I just can't understand it! Could some of you who understand try and give me some analogies or anything that might help me out? Thanks alot!

Interesting new jet plane has rolled out of its hanger. https://img.purch.com/h/1400/aHR0cDovL3d3dy5zcGFjZS5jb20vaW1hZ2VzL2kvMDAwLzA2Ni80NjMvb3JpZ2luYWwvZHJvbmUxX3dlYnNpdGUuanBnPzE0OTYyNjgyNTY= It looks like there are vibration modes of the plane that during normal operation would shake the...

Homework Statement An intrinsic semiconductor with a direct gap have valance band ##\epsilon_k = E_v-b|k|^2## and conduction band ##\epsilon_k = =E_c+a|k|^2##, with ##E_v=6.0##eV, ##E_c = 5.5eV##, ##a=5.0eV\cdot Å^2##, and ##b=3.0eV\cdot Å^2##. Calculate the chemical potential ##\mu## and the...

Hello Physics Forums I’m doing some numerical studies on diffusion. I began with monte carlo simulations on gas diffusion, and more recently I’ve started to dabble in carrier diffusion inside semiconductors. It looks like diffusion in semiconductors is a lot more amenable to experimental study...

Homework Statement A metallic film has length L=10mm, width W=1mm and thickness t=1##\mu m##. The current is parallel to the long edge and has magnitude ##I=0.7A##. Longitudinal voltage is ##V=1V## and it doesn't change with magnetic field. The Hall (transverse) voltage ##V_H## increases at...

Homework Statement Homework EquationsThe Attempt at a Solution Current is I = nqvA so drift velocity V is: V = I/nqA Drift velocity for x is: Vx = I/nqA Drift velocity for y is: Vy = 2I/nqA So the ratio of Vx : Vy should be 2:1 since Vy is equal to 2 lots of Vx?? (but correct answer is B)

I need clarification on the difference between a “force carrier” and “radiation.” Imagine two electric charges separated by a distance “d” but not moving. They exchange “force carrier” photons which tell the electric charges to attract/repel. But you can’t see these “force carrier” photons...

Hi all, I'm reviewing device physics and I would like to understand how majority and minority carrier concentrations for both N- and P-type substrates change with temperature. My reference, Pierret's Semiconductor Device Fundamentals, has this figure: and I want to generate curves for all...

Hello everybody, I'm a little bit confused about two types of amplitude modulation. We distinguish here: Case I : Amplitude Modulation with suppressed carrier (https://en.wikipedia.org/wiki/Double-sideband_suppressed-carrier_transmission): Case II : Amplitude modulation with carrier: Now...

Suppose I have an n-doped semiconductor and want to measure the electron concentration in the conduction band as a function of temperature. How would I go about doing this by measuring the Hall coefficient as a function of temperature, given that I don't know the electron and hole mobilities...

Please check the following questions. Steady state of semiconductor w.r.t excess carrier. 1. If we shine photons on semiconductor and then turn the light off, semiconductor is not under the steady state condition. (it is under transient state since excess carrier concentration is decreasing)...

I have a few questions about AM, FM and PM. 1. If FM (or PM) radio modifies the frequency of the signal, how is the signal picked up without having to change the frequency constantly? 2. If PM modulates phase, which modulates frequency, what is the difference between PM and FM? 3. Why is AM...

Homework Statement The question is in the picture attached. When Na=0, that means the acceptor concentration(i.e. open holes?) is zero? Homework Equations (Nd-Na)/2 + sqrt((Nd-Na/2)^2+ni^2) (Na-Nd)/2 + sqrt((Na-Nd/2)^2+ni^2) The Attempt at a Solution Solving for Nd=10^8: majority carrier =...

Homework Statement [/B] Keep in mind this is a Top Gun-themed homework assignment. Cougar comes in for a shaky landing. His 20422 kg airplane traveling at 85 m/s strikes the deck at 3.5 degrees below the horizontal. Cougar's plane snags the landing cable stretched across the deck. The landing...

< Mentor Note -- thread moved to HH from the technical physics forums, so no HH Template is shown >[/color] I am following a lecture on carrier concentration and I got to the point where the instructor said that for homework, derive the carrier concentration equation ni, which...

Let A= (sin(x) * sin(100x)) + sin(100x).; modulation index is 1; Let B= (sin(x) + sin (100x)); Both of these waves have same frequency and both are amplitude modulated. When passed through an envelope detector, both will give message signal. And B have an advantage of not having any sideband...

I need to calculate the refractive index of a semiconductor material over a wavelength range (1×10-5m - 1×10-9m) and with different values of electron and hole carrier concentrations (i.e. n/p doped). I found this equation that relates those parameters: n+ik = √ [ (εm -...

A thought experiment that is a consequense of a question someone asked in my particle physics class: We place an isolated electron. We wait 10 years, and place a half ring of electrons (spaced far apart from each other, but uniform) 10 LY away from our central e. Will our charges move? If so...

Every gauge boson is within a field and carries a force. Higgs is a scalar (spin 0) boson. I am not sure which category a graviton (spin 2) would fit into, but it surely would carry a force. Is it possible that Higgs carries a force that we have not recognized yet?

I would like to know how carriers flow in a bipolar junction transistor when working in saturation mode. Normally, electrons would flow from the emitter to the base. Then, from the base, some recombine with holes nad leave, forming the base current, and the others (the majority) diffuse in the...

I am little bit confused about derivation for Boltzmann equation for electron look at this link http://relativity.livingreviews.org/Articles/lrr-2008-10/articlesu25.html which is final boltazmann equation ?

What is a typical carrier frequency for amplitude modulation? In particular, for amplitude modulation in spectroscopy.

Perturbation theory predicts rates of transitions between eigenstates of the unperturbed Hamiltonian, which in the independent electron model for a crystal are nonlocal Bloch wave functions or linear combinations of them that extend throughout the crystal. However, photon absorption is...

I have the following data in an epicyclic gear train: Angular speed on ring = 1500 rpm, teeth on ring = 30 Angular speed on sun = 3200 rpm, teeth on sun = 10 Angular speed on carrier = 1925 rpm, teeth on planets = 10 (The ratios of teeth are for simple calculation assumed 3: 1: 1 among...

Can somebody please give me a little more detailed explanation of a simple Feynman diagram? It's not clear to me why the owner particle experience any force? Let's check out 2 electrons interacting by a virtual photon. 1) 1st e is moving along, throwing gazilions of virtual photons but nothing...

Homework Statement Given a DSB -SC system, with a message limited to B Hz, what is the minimum usable value of ωc or f0 (carrier frequency) Homework Equations Nyquist theory? Not sure how to apply. The Attempt at a Solution Only attempt has been through research.

HELLO everybody and thank you! My name is Hakim, 27-years, I'm a Moroccan graduated in computer science (specified in programming) with my master and I'm actually doing great... My fascination with physics and science is deep... But I never studied any kind of physics or maths in school...

I'm going to be working on a research project for an internship that involves photo-generated carrier dynamics, and after looking up the topic for a while, I haven't been able to find a source that explains what it is/means. I'd appreciate if anybody could take a minute to explain this concept...