Cell Definition and 899 Threads

Hi, I have a standard cell which I would like to rotate. I would like to rotate it in such a way such that when I define some plane in the unrotated cell [hkl] that this same plane corresponds to the [001] plane in the rotated cell. I essentially want to keep the same unit cell, just rotate the...

Farady's law are derived for electrolysis. My question is the same rule can be applied in the analysis of electrochemical cell? I think those two cell (electrolytic and electrochemical) are just opposite functional to each other.

hello i got to ask if the center of symmetry is specific to a unit cell or a pattern or system of specific unit cell? I mean is Cubic (Bravis Lattice) is Centro symmetric or the structures formed by it. As an example, Tetragonal unit cell appears centro-symmetric but forming structures like...

Here,I have a pre-defined function called 'intersections(x,...) that finds the intersections between 2 functions of x.Now,for each iteration of the loop,I get a set of (x,y1) and (x,y2) values. I want to store them in an array without losing the previous iteration's values. So,I figured I'd use...

Homework Statement Hi, So I have this problem regarding a photovoltaic cell I found part 1 easy and part 2 wasn't actually too bad either but I couldn't finish the calculation. I managed to get to the stage where I have an integral , the problem is that the upper limit is infinity and I'm...

I asked this question in Yahoo Answers but I didn't think that the responses were very good This is just for my own knowledge I wanted to know if let's say for instance that I had a rotary device, clamp right on the center of mass of my phone and it spun rapidly... could the phone spin so...

Hi all, one last question for today - Given steam reforming of natural gas to generate hydrogen, what is the major difficulty with it with respect to most fuel cells? Thank you,

Hi, Given that the band-gap of a silicon PV cell is 1.1 eV, what is the maximum wavelength of solar energy (minimum frequency) required forming an electron-hole pair (EHP)?

Can anyone help me explain the elements of the fuel cell polarization curve. Please be sure to include Etn, Er, and the various polarizations. I am interested by the use of thermodynamics as well... Thank you-

I would like to understand exactly what happens when a PN doped crystalline silicon cell is shaded.Lets assume we have ten solar cells wired together in a series string.That there is plenty of sunlight on the first nine cells but cell ten is completely shaded.Lets say the forward bias of each...

Homework Statement Calculate standard potential for a Cu2+ 0.5M, Zn2+ 0.5M cell.Homework Equations Ecell = E0cell - (RT/nF)lnQThe Attempt at a Solution So, I know at standard conditions it would simply be Ecell = 0.340 - (-0.763) Ecell = 1.103 It's the concentrations that are confusing me. If...

Hello all. As the title has informed you, I wish to make an water electrolysis cell that can not only produce hydrogen, but also store it completely separate from the oxygen (Again, I promise you, it is not for fuel. Now, your probably wondering why I don't just make the typical...

Hello Please help me with this. Cathode has negative charge, anode has positive charge. Electrons travel from anode to cathode. Question 1: why is anode positive and attracts anions? How can the charge build up on this electrode if electrons are constantly flowing out of this electrode...

In statistical mechanics, nearly all the textbooks say that the volume of the smallest cell in the phase space of a N-particle system is h^{rN} where h is the Planck Constant, r is the degree of freedom. Also these books say that this comes from the uncertainty principle. However, the...

Hi everyone, I was just wondering how I would choose which species in an electrolytic cell to use as the cathode and which to use as the anode. For example, for aqueous aluminum chloride (inert electrodes), H2O (-0.83V) and H2O (+1.23V) will be used as the anode and cathode for the half...

Greetings everyone, I am taking a course on elementary condensed matter physics and our textbook is "Introduction to Solid State Physics" by Charles Kittel. I have read the crystal structure from 4 books; however, I am still confused about the definitions such as unit cell, primitive vector and...

I'm trying to learn more about how cell phones operate. Right now I don't understand the power involved in the signal between the cell site and mobile phone. I've read that the average cell phone has a signal strength that ranges in between -80dBm and -120dBm. I've also read that cell phones...

I've heard fuel cells being called energy storage devices. However, unlike batteries, they only convert energy. They don't store anything unless you consider the brief moment of converting chemical energy to electrical energy storage time? Are there fuel cell types that store let's say hydrogen...

Hi. I'm doing research relating to solar cells and came about the topic related to effective masses. The wiki article stated how effective mass (solid state materials) influences the efficiency of solar cells, but doing more research I couldn't find any solid examples of an effective mass vs...

So today my brother and I were playing with a mini solar cell that I just got, watching the voltage change with a multimeter, and seeing how even an LED would produce about .5 V in the cell, when he posed a question: If you were to take a solar cell (i.e. photodiode) capable of producing...

Homework Statement During an action potential, Na + ions move into the cell at a rate of about 3 x 10^-7 mol / m^2 s. How much power must be produced by the "active Na+ pumping" system to produce this flow against a + 30 mv potential difference? Assume that the axon is 40cm long and 30 mu m...

Hi! My brother has a small micro-heater that runs on a single AA battery. The battery life tends to be rather short so we started using rechargeable batteries. The rechargeable batteries are marked as 2000mAh and since they're AA and Nickel-metal Hydride I'm guessing they operate at 1.25v...

I'm a biology dilettante who is trying to get a correct picture of the cell. From this web page http://www.arcfn.com/2011/07/cells-are-very-fast-and-crowded-places.html one gets a very chaotic impression. Small molecules are racing around with 250 miles per hour. Ken Shirrif: "In addition, a...

[FONT="Arial"]hello PF community i'm looking for help in understanding the classification and observed behaviour of some DIY voltaic (?) cells and their associated circuits with which I've been tinkering for a couple of years the cell operation seems to belong somewhere between galvanic...

I have a very small solar cell that outputs 4 volts (open circuit) and 50 μA (short circuit). I'm trying to charge a 0.33 F capacitor that is rated for 5 volts. I'm looking to understand the charging relationship. 1. What equations govern the charging of this capacitor? I'm already aware of...

I don't understand this idea. For example we have cubic crystal which has a lot of unit cells. We define spin variable of center of cell like S_c. And spin variable of nearest neighbour cells with S_{c+r}. So the cell hamiltonian is...

Very cool! I just started using my new femtocell connection from AT&T. It provides a cell connection for a range of about 10 meters, using an internet connection. It seems to work great. The connection is solid with 5 bars, and the sound quality is excellent. I have been playing dueling phones...

Hi, I want to continue my study in physics, but i have to find topics for research proposal, and I need your help. I hope you can give me the news about the newest research in solar cell? the material or new method? thanks for your help...:smile:

A Galvanic Cell is given. Write its Anode and Cathode half reactions, complete cell reaction and thus determine if the given is concentration cell. Pt|O_2(1\; atm)|NaO\! H(10^{-3}M)||H_2SO_4(0.5M)|O_2(1\;atm)|Pt I know that at anode, Oxygen will get oxidised, maybe from NaOH solution and...

What are some good documentaries on cell theory cell membranes DNA or genetics.Also documentaries on bacteria and viruses would be good.

I've recently gained an interest in solar cells and it's development. I know the basic working principle of solar cells, but other than that I'm quite clueless about the field. I was wondering, what is the process of increasing solar cell efficiency like? Are there analytical ways of...

Recently I saw an article about sled dogs burning 10,000 calories in a day. Even when adjusted for mass, this is significantly more energy than a human athlete might use. This got me thinking: how much energy do bacteria use in a day? Trees? Fungi? Other animals? I can think of lots of...

Homework Statement Knowing that sodium has a BCC structure, a density of 970 kg/m^3 and each atom has an atomic mass of 22.98 amu, determine the length of the primitive cell. Homework Equations Not sure. The Attempt at a Solution I calculated how many atoms of Na there is in 1m^3...

So, here is my question we know about an electrochemical cell in which when zink rod and copper rod are dipped in there respective solutions the electron flow from zink rod to cu ... but what makes those electron to flow ... here comes the answer the potential difference did that ... please...

I read in a book concerning cell biology: "Many enzymes are also greatly affected by the precise chemical environment around them." I understand that enzymes are affected by their respective environments. The book's sentence seems to indicate that different environments exist in the...

Why do cell walls such as in an herb become brittle when dried? What is water doing exactly to hold it together before it was dried?

or can synthetic dna give life to a dead cell. i.e when scientist removed genetic material of a cell, didn't the cell died. And when this synthetic genome is injected into the nucleus, it survive. Is this what happened.

Suppose I only have a conventional cell with atomic positions obtained from a structural database, and I need to know the primitive cell for that lattice. Is there some general way to reduce the conventional cell to the primitive cell? That is, to determine the correct primitive vectors and...

Let's say I have a balloon full of Hydrogen that is STP, and outside this balloon I have normal air (containing oxygen) which is also STP. Is there a way to produce energy by turning these 2 items into a fuel cell, if so how practical is it (in a DIY setting) and is there anything that would...

Homework Statement Calculate the cell potential at 25°C for the cell: Fe (s) | (Fe^2+ (0.100 M) || Pd^2+ (1.0*10^-5 M) | Pd (s) given that the standard potential for Fe^2+/Fe is -0.45 V and for Pd^2+/Pd is +0.95 V. A. +1.28 V B. +1.16 V C. +1.52 V D. +1.68 V Homework Equations E Cell...

This has been a well known problem that has caused millions of dollars of research and thousands of man hours to be wasted. Is HeLa cell contamination still a huge problem that people still don't bother to check for? Are there certain vendors that verify cell lines for this contamination...

Hi, Just wanted to know from any electrical engineers out there why it would be hard to redesign the common cellphone chargers to not draw current when the device is plugged out of it. My EE knowledge is not great, but wouldn't it be possible to put a "switch" before the primary coil that...

Homework Statement Homework Equations The Attempt at a Solution I always thought you put the electrolyte of one half cell on one side and the other electrolyte on the other side The answer given is C. But this includes VO2+ which is not in the initial eqn on the RHS?

Homework Statement A voltmeter is connected across a cell in a circuit containing a switch and a 2Ohm resistor. When the switch is open, the voltmeter reads 12V. When it is closed, the reading is 8V. Find the internal resistance of the cell. Homework Equations I tried to use V=IR - is I...

I am helping my son do a project. We would like to know how to increase the output voltage. For example we have three 6 volt 50ma cells and would like to make 18 volts

In a cell circuit, conventional current flows from the +ive terminal to the -ive terminal. In which direction is the emf?

Horrendous: Source: DEA Ignored All My Cries: Student | NBC San Diego http://www.nbcsandiego.com/news/local/daniel-chong-ucsd-san-diego-dea-149758275.html

Hey guys, 1. basically I am using the silvaco athena and i got some code to make the solar cell simulation. and my project is basically about designing pn junction in terms of the solar cell. kinda clueless of what are things that i need to modify in the code to make sure that i have a good...

I do not know to which section this question belongs correctly. The question is : How does our cellphone calculates or knows the percentage of battery left?

How can you measure voltage - my friend confused me. We all know we can do it by a voltmeter but a voltmeter is a galvanometer and we need to know the resistance of the galvanometer and current passing through it to find voltage But to find out resistance we need to know current and voltage -...