What is Carrier: Definition and 139 Discussions

The escort carrier or escort aircraft carrier (U.S. hull classification symbol CVE), also called a "jeep carrier" or "baby flattop" in the United States Navy (USN) or "Woolworth Carrier" by the Royal Navy, was a small and slow type of aircraft carrier used by the Royal Navy, the United States Navy, the Imperial Japanese Navy and Imperial Japanese Army Air Force in World War II. They were typically half the length and a third the displacement of larger fleet carriers, slower, carried fewer planes, and more-lightly armed and armored. Escort carriers were most often built upon a commercial ship hull, so they were cheaper and could be built quickly. This was their principal advantage as they could be completed in greater numbers as a stop-gap when fleet carriers were scarce. However, the lack of protection made escort carriers particularly vulnerable, and several were sunk with great loss of life. The light carrier (U.S. hull classification symbol CVL) was a similar concept to the escort carrier in most respects, but was fast enough to operate alongside fleet carriers.
Escort carriers were too slow to keep up with the main forces consisting of fleet carriers, battleships, and cruisers. Instead, they were used to escort convoys, defending them from enemy threats such as submarines and planes. In the invasions of mainland Europe and Pacific islands, escort carriers provided air support to ground forces during amphibious operations. Escort carriers also served as backup aircraft transports for fleet carriers, and ferried aircraft of all military services to points of delivery.
In the Battle of the Atlantic, escort carriers were used to protect convoys against U-boats. Initially escort carriers accompanied the merchant ships and helped to fend off attacks from aircraft and submarines. As numbers increased later in the war, escort carriers also formed part of hunter-killer groups that sought out submarines instead of being attached to a particular convoy.
In the Pacific theater, CVEs provided air support of ground troops in the Battle of Leyte Gulf. They lacked the speed and weapons to counter enemy fleets, relying on the protection of a Fast Carrier Task Force. However, at the Battle off Samar, one U.S. task force of escort carriers and destroyers managed to successfully defend itself against a much larger Japanese force of battleships and cruisers. The Japanese met a furious defense of carrier aircraft, screening destroyers, and destroyer escorts.
Of the 151 aircraft carriers built in the U.S. during World War II, 122 were escort carriers, though no examples survive. The Casablanca class was the most numerous class of aircraft carrier, with 50 launched. Second was the Bogue class, with 45 launched.

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  1. H

    Calculate Minority Carrier Concentrations given the Fermi Level

    Homework Statement This question is based on a previous question in the same homework: The Problems deal with Silicon at 300K, using band gap energy Eg = 1.12 eV, electron density of states mass 0.327, hole mass 0.39, electron mobility 0.15 m2/Vs, hole mobility 0.05 m2/Vs and relative...
  2. V

    How a force carrier particle gets a message to its owner particle?

    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...
  3. S

    Min carrier frequency in Amp Mod.

    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.
  4. HakimPhilo

    [Quantum_Mechanics] Not too old to start a carrier in this Wfield

    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...
  5. W

    Photo-Generated Carrier Dynamics?

    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...
  6. F

    Virtual photons and long range force carrier

    It is often said that the photon is the long range force carrier like the static force between electrons. Let's say we have two electrons galaxy apart, wouldn't the virtual particles have to travel long distances and "virtually" become real. And isn't the first sentence is wrong anyway since...
  7. M

    Is light a carrier to bring all the way of motion image of dead star?

    Hi Friends, I am Alen, doing research about light. I have submitted my thesis which contains few finding about light and utilizing maximum solar energy to produce electric energy from few square feet area. I got permission from my adviser to discuss on internet forum. I hope your commands and...
  8. L

    How do I generate a broadband or wideband carrier?

    Generating a carrier on a single frequency is simple, just use an oscillator of a specific frequency and amplify. But how do I generate a carrier that is 100KHz wide, or even 100MHz wide? The obvious answer is more oscillators, but is there a better way?
  9. S

    Free carrier absorption in GaSb

    Homework Statement Given the carrier concentrations (1.4x10^16, 3.2x10^16 and 5.3x10^16 /cm^3), verify that the free carrier losses scale linearly. (use λ=10μm) Homework Equations Those concentrations are given by this paper: A. Chandola, R. Pino, and P. S. Dutta, "Below bandgap optical...
  10. P

    Charge carrier injection in heterostructures - help with concept definition

    Hi, I have this report to do on "Charge injection in heterostructures". I have been searching and reading but I still have some trouble with the basics, i.e. defining the concept. As far as I understood a heterostructure is a junction between two or more different semiconductors and the...
  11. S

    Semiconductor Physics : Charge carrier concentration change on doping

    Hi, I have a question regarding the change in charge carrier concentration change. For a given semiconductor, say Silicon, when it is not doped, it is easy to understand that {n_0} \times {p_0} = n_i^2, however, on doping with donors to form a n-type semiconductor, we have {n_0} \approx...
  12. C

    Exchange force carrier between two protons

    I know that the virtual exchange particle between two electrons is the photon and this explains why they repel each other (ie virtual photon is spontaneously emitted from one electron A causing it to recoil. As the virtual photon hits electron B, it imparts momentum causing it to move away so...
  13. M

    Charge carrier screening in semiconductor

    Dear physics forums users, I'm reading a paper saying "For hole density p\sim 10^{17} - 10^{18}/cm^3, the screening length in silicon, \lambda_{Si}, is ~1-2nm." For this, the paper references Sze's, Physics of Semiconductor Devices. I'm unable to find the formula by which the authors seem to...
  14. T

    Transparent paint carrier of electrical current

    Hello ... Please , I want a transparent paint for a glass or plastic that carrier of electrical current. If it is existing in market ( what is the brand name) or there is a way to be manufactured by local materials available. Another question ... Is there a dry metal compound (powder)...
  15. A

    How photon is force carrier of electromagnetic force in macroscopic level.?

    i have gone through that photon is force carrier of em force..but in macroscopic level as far as I studied I know em force is designated with field in macroscopic rather than a particle like interaction.so how can they justify that em force is managed by photon.If photon is more plausible is it...
  16. I

    Envelope, carrier and beat frequency equations?

    Hello, What are the equations used to calculate the carrier, envelope and beat frequencies? Thanks
  17. A

    Intrinsic carrier concentration formula

    In the ni=\sqrt{Nc*Nv}*e^{\frac{-Eg}{2kT}} formula for intrinsic carrier concentration, what values Nc,Nv and Eg take in relation to temperature? Are they each calculated for that temperature or, for example, is Eg always taken for 300K? My guess is they should all be calculated for given...
  18. B

    Measuring the density of an aircraft carrier

    An object floats if it is less dense than water. I'm assuming that an aircraft carrier can float because there are several rooms in it with air. What happens when the door on the upper most floor is opened? Does the air inside that room still contribute to the total average density of the...
  19. A

    Electron-Hole Concentration vs. Carrier Density

    I'm a bit unclear on terminology with semiconductors: is there a difference between the "intrinsic carrier density" and the "electron concentration" or "hole concentration"?
  20. A

    Force Carrier for Electromagnetism

    Can anybody give me or point me to a model that describes how electromagnetism works from a photon force carrier perspective. I like to know how the virtual photons are generated around an electron. Also why electromagnetism is polar. I am also confused why moving electric fields create magnetic...
  21. L

    Carrier Swing & Deviation Ratio: Clarifying the Definitions

    Can anyone help me to find out the definition of "carrier swing"&"deviation ratio"? The definitions which i found on surfing the net is too vague.Can someone help me with this?
  22. M

    Pulsed wideband SNR problem solved by a dynamic carrier?

    I am disappointed by the fact that receiver noise seems to be directly proportional to bandwidth. With a raised cosine shaped pulse transmitter the bandwidth is the more or less the reciprocal of the pulse duration. Short pulses mean large bandwidths and that means greatly reduced range, at...
  23. rhody

    Carrier IQ Your cell phone's secret big brother

    I have been following this story for awhile, and since no one is reporting it, I thought I would post, because I feel you should be aware of what you may be subjected to when you use your cell phone. Have a look, comments, disbelief, outrage...
  24. C

    Are force carrier particles emitted by mass or created by fields?

    My general understanding was that they were created by fields, which makes me wonder how the LHC plans to detect the higgs boson... but I could be wrong
  25. P

    Physics Should I choose physics as my carrier?

    I'll elaborate. This year, in high school I started studying physics for the first time ever - I know, Mexico's Educational System is one of the Worst :\ - And I really, really liked it. The thing is, right here in mexico it is really hard to make a living as a physicist, and It's really...
  26. R

    How to Create a 90-Degree Turning Infield Carrier for Motorcycles

    how to joint two cylinder shaft which can make it turn 90degree anyone can give their opinion for me? :D
  27. Ranger Mike

    Is China's New Aircraft Carrier Design Real or Just a Virtual Concept?

    I got this from a friend over the internet...is this design practical or just some virtual design?
  28. U

    Low single charge carrier density materials?

    Hello all, I am trying to identify materials having a single dominant charge carrier having extremely low (on the order of 10^15 cm^-3) concentrations. Metals and extrinsically doped semiconductors, while both possessing a single dominant charge carrier (electrons or holes), tend to have...
  29. I

    Carrier injection in p-i-n diodes

    Hello all I have a p-i-n diode structure. I am applying a forward bias to diode, so that holes from p region, and electrons from n region are injected inside the i region. Now, I need to find a relationship between the applied bias/current vs the number of holes and electrons that are...
  30. R

    Find the intrinsic carrier density

    Homework Statement The effective masses of n- and p-carriers in a semiconductor are given by mn* = 0.067me and mp* = 0.48me respectively. The gap width of the semiconductor is 1.45 eV. Use this information to find the intrinsic carrier density at 440 K. Homework Equations I have no...
  31. H

    Equilibrium fermi level and carrier concentration

    Problem statement: Determine electron and hole concentrations in Si at room temperature given that the Fermi level is 0.20eV above the valence band energy. So my thoughts on this problem: First we draw the band diagram, and it's clear that this is P type. Then, p0 = Nv * exp((Ef - Ev)/KT)...
  32. M

    Derivation of carrier density formula

    Hi there, Not sure if this is in the best section, but here goes... I'm trying to establish how a formula from a paper I have read has been derived. The formula is: n=\frac{1}{qV} \int_0^I{\tau} dI where n is the carrier density, q is the elementary charge, V is the volume of the...
  33. S

    What is the Acyclic Carrier Theorem and how can it be applied using chain maps?

    This is theorem 13.6 in Munkres' Elements of Algebraic Topology. I'm trying to go through this, but I can't prove it. Can someone do this one please? Btw, its "Choose a partial ordering of the vertices of K that induces a linear ordering on the vertices of each simplex of K. Define...
  34. P

    Frequency of the carrier wave changed during amplitude modulation

    While reading about frequency modulation, I found that it was clearly written that the amplitude of the carrier wave remains unchanged. However, i didn't find a statement stating that the frequency of the carrier wave remains unchanged for amplitude modulation. So, is the frequency of the...
  35. E

    Calculating Force on Aircraft Carrier John F. Kennedy

    Homework Statement The aircraft carrier John F. Kennedy has mass 7.4*10^7kg. When its engines are developing their full power of 280000 hp, the John F. Kennedy travels at its top speed of 35 knots. If 70% of the power output of the engines is applied to pushing the ship through the water...
  36. M

    Semiconductor Carrier Concentration Basics

    I have been told that the relationship n.p = (n_i)^2 always holds, where n_i is the intrinsic carrier concentration. This makes sense to me for an un doped semiconductor (sc.). However, for a doped sc., I'm a tad confused. For an n-doped material say, the electron conc. is...
  37. B

    How do you calculate carrier concentration in a doped semiconductor?

    I have a homework on Solid state device the question is :"If a Si sample is doped with 10^14 boron atoms per cm3 then determine the carrier concentration in the Si sample at 300K."[/b] I thought that the concentration is calculate by n = 2[(2pi*un*kT/h^2)]^(3/2) is this right formula ...
  38. B

    Understanding ADSL DMT Carrier Waves: Questions & Answers

    Hello, I am hoping someone out there can me better understand how an ADSL DMT carrier wave works. Is the carrier wave made of photons or electrons? I have tested the dry loop at my house and from what i can tell this is not an electrical circuit, but two open wires. This begs...
  39. S

    Time as the force carrier of mass

    could time be the force carrier of mass? in other words maybe time is to mass sort of what electromagnetism is to photons. if so then we won't find a the Higgs boson because there isn't a conventional particle to detect. can we treat time like a particle in existing models?
  40. R

    Hall Effect charge carrier trouble

    Hello. I recently did a Hall effect experiment with InSb. I did it in two parts. The first with the sample at room temperature and the second immersed in liquid nitrogen. I need some help understanding my results. I used the fomula v_h = (v_1 - v_2) / 2 to work out the Hall voltage (v_h). v_1...
  41. R

    Exploring the Practical Uses of Band Gaps and Free Carrier Absorption

    what is the practical use of the concept of band gap other than classification between material? can free carrier absorption be manipulated by changing band gaps?
  42. R

    Carrier transport in semiconductor

    Homework Statement in Intrinsic GaAs,electron and hole mobility are 0.85 and 0.04 meter square/volt-sec and corresponding effective mass are 0.068m and 0.5m, where m=9.11*10^(-31)kg. band gap energy is 1.43 eV at 300K. ---calculate intrinsic carrier concentration(!) and Conductivity. Homework...
  43. G

    Low temperature LCC chip carrier

    I need a LCC for low temperature measurement down to 10K or at least 77K. but I couldn't find any LCC capable of operating at that low temp. most commercially available LLC can only operate -70C. how you guys find a LCC operating below 77K? is it custom made?
  44. M

    Doped Si carrier concentration

    Hope you can give me a hand here guys. I'm finding the whole carrier concentration thing a bit confusing! Si doped with say 10^17 P (/cm3). At 300K, calculate n, p, E_F (Fermi energy). Now I know the relations such as n=(N_c)exp[(E_c-E_F)/kT], N_c given I just can't figure out...
  45. U

    What is the charge carrier density in the conductor

    The Hall voltage across a 0.800-mm-thick conductor in a 1.30 T magnetic field is 3.2 uV when the current is 12.0 A. What is the charge carrier denisty in the conductor (in m-3). I was using the equation Vh=IB/ned where Vh is the Hall voltage I is the current B is the magnetic field...
  46. M

    Carrier wave frequency spectrum

    Homework Statement The Attempt at a Solution The carrier wave is by inspection 0.5 + cos(10\pi*t) and the other would be 1.5*sin(60\pi*t). I'm not entirely sure what we're supposed to graph for the second part, the frequency spectrum. Any help?
  47. J

    Biological carrier wave signals

    hi yea umm is there any research/thinking regarding carrier wave signals being transmited vocally? jb
  48. FeDeX_LaTeX

    Force carrier particles i.e. gravitons, photons

    Hello; How do force carrier particles work? For example, if I drop an object, the force of gravity is carried by gravitons. Does this mean that there is a long stream of gravitons underneath/all around the object? Because the wave would need to be carried through the medium of gravitons. Is...
  49. L

    What Does "Electron Carrier" Mean?

    Hi all, I have a very basic question. I see a lot of "electron carriers" or "carrier electrons" terminologies. What does they actually means? Are they telling that electron as carrier for current? Because I thought that current is electrons that move from a point to another point, and that's...
  50. R

    Second degree DE for pn-junction carrier concentration

    Upon some calculation I arrive to the expression: d2DPn(x)/dx2 = DPn(x)/Lh2 Where: DPn(x) = Pn(x) + Pno - excess minority carriers (holes) concentration in the n-type part of the pn junction. Now the roots to the characteristic equation are +/- 1/Lh where Lh is the length of the...
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