Base Definition and 571 Threads

Greetings. I am trying to understand the common base amplifier better so I can build a preamp for a low impedance guitar pickup. In order to explore its operation, I tried to model it with the "approximated" Ebers-Moll model (from the wikipedia page on BJT's) and the graphing program in Mac OSX...

Homework Statement Which of the following species is the strongest base? A. NH2- B. OH- C. Cl- D. NH3 E. I- Homework Equations The Attempt at a Solution Ok I know that Cl- is a very weak base so I know it is not that one for sure. I want to say that the answer is NH2-...

Hi to you all, I'm reading about semiconductor devices on Muller-Kamins' "Device Electronics for Integrated Circuits" and I have some problem understanding the base transit time of a bipolar transistor. I read that when the npn bjt is forward biased the emitter injects electron in the base. In...

Homework Statement Hi everyone I need help for this problem : If 2*\log_2 (x-2y)=\log_3 (xy) , find \frac{x}{y} Homework Equations \log_bx = \frac{\log_ax}{\log_ab} The Attempt at a Solution 2*\log_2 (x-2y)=\log_3 (xy) \log_2 (x-2y)^2=\log_3 (xy) \frac{\log_2...

Hi All, I can't see how the following is proved. Given two topological space (X, T), (Y, U) and a function f from X to Y and the following two statements. 1. f is continuous, i.e. for every open set U in U, the inverse image f-1(U) is in T 2. For every convergent filter base F -> x, the...

hey guys, i have a question, then i will show my solution, is there any chance you guys could help me find an easier way to get to the answer, cheers question: log_3 3x answer: log_a (yx) = log_a (y) + log_a (x) log_3 (3) + log_3 (x) log_a (y) = x -> y = a^x -> log_a (a) = 1...

Hello PF I hope you can give me some guidance. This is something that I am getting more and more on my desk, to be honest I don't understand it enough to give an answer. I have searched the net looking for an answer but can only find details on fulcrum points class 1,2 & 3 which does not seem to...

Homework Statement Hi, I am trying to prove for a>1, b>1 that f(x) = O(log_b(x)) then f(x) = O(log_a(x)). [Hint: log_b(x) = log_a(x)/log_a(b)). Homework Equations The Attempt at a Solution Assuming |f(x)| <= C|log_b(x)| true for x>k, then, f(x) <= log_a(x)/log_a(b)| for all x>1...

I have just begun studying differentiaition and I was getting confused with how to differentiate a function of x in which x is in the base and is in the exponent as well (for example, x^2x) with respect to a=hte cahnge in 'x'. I remember my teacher telling me something about applying log...

Hi folks - I'm trying to follow along in a textbook the derivation of the common-base current gain equation, and I'm having a bit of trouble. The common base current gain is supposed to be approximately \alpha, where \alpha = \frac{\beta}{\beta+1}. Doing a nodal analysis with the signal applied...

I am calculating the likelihood of a hierarchical model and am having trouble distributing the product sign. Here are the two expressions that I'm interested in: Product from j=1 to j_k of: (t_jk)^(sum(Z_ijk) + a_k - 1) and Product from k=1 to K of: (b_k)^(j_k*a_k). The tricky...

I am calculating the likelihood of a hierarchical model and am having trouble distributing the product sign. Here are the two expressions that I'm interested in: Product from j=1 to j_k of: (t_jk)^(sum(Z_ijk) + a_k - 1) and Product from k=1 to K of: (b_k)^(j_k*a_k). The tricky...

Hi, I am trying to represent my data in log2 form rather than "fold change" and I am embarrassed to say I can't remember how convert the error. For example, I have x=3.96 (mean), deltax=0.28 (standard dev). Thus, log2(x)=0.598. But how do I convert the error?? I know how to do it for...

Homework Statement Forward resistance of the Base -Emitter Junction showed a value of 12ohms when it was measured by (x1) resistance scale of an analogue multimeter .And it showed 70ohms when it was measured using (x 10) scale factor .The variation in the two readings occurs due to...

Homework Statement Which of the following, Na3PO4 or C2H4(OH)2 could produce a pH curve with two buffer zones? The Attempt at a Solution I think the answer is Na3PO4 because it can react twice, but the third reaction may not complete. C2H4(OH)2 is ethylene glycol. Is it possoble for it to...

Homework Statement In this experiment you will find the ionization constant for ammonia, a weak base. I have completed the experiment, and have the following: Initial concentration of NH3: 3.708mol/L Initial pH of NH3: 10.26 Homework Equations NH3(aq) + H2O(l) <--> NH4+(aq) +...

Homework Statement Calculate the pH after 24 mL of 1.00 M NaOH is added from the burette to a beaker containing 25.0 mL of 1.00 M HCl Homework Equations pH = -log [H+] 1*10^-14 = [H+][OH-] The Attempt at a Solution combined volume = 49mL n.unreacted(H+) = 0.025-0.024 = 0.001...

Homework Statement I am trying to plot base characteristics using mathematica. The characteristic equations are: Homework Equations \frac{dx}{d\tau}=x u(x,y) \frac{dy}{d\tau}=y u(x,y) \frac{du}{d\tau}=x^2+y^2 u(x,1)=Sqrt(x^2+1) Initial Data The Attempt at a Solution How do I solve this...

Homework Statement Problem is this. I am tasked with deriving a formula or equations that I can then input into an excel format. I am to take an equipment base that has four sides with supports at each of the four corners. I am to find the load that each one will hold base upon the Center of...

Homework Statement Write two equations that illustrate that an aqeous solution of NaHCO3 can act either as an acid or a base. In pure water show quantitatively which of the two reactions predominate. ka1= 4.2x10-7, Ka2=4.8x10-11 The Attempt at a Solution as an acid: NaHCO3(aq) +...

Why is the idea of putting a station in orbit more appealing then putting on on the moon? I understand the want to test things in low gravity. But what about cost wise? I know that the ISS has to change it's direction every now and then to avoid random junk floating in space, and I understand...

N is a seven digit base-8 positive integer having the form ABCDEFG that uses each of the nonzero base-8 digits 1 to 7 exactly once, and satisfies these conditions: (i) ABCDEFG is divisible by 7. (ii) ABCDEF is divisible by 6. (iii) ABCDE divisible by 5. (iv) ABCD is divisible by 4. (v)...

Homework Statement The e.m.f E of a battery is given by E = \frac{P}{I} where P is the power supplied from the battery when current I flows through it. An e.m.f. {E_c} can also be induced in a coil when the magnetic flux, \Phi , associated with it changes with time, t, as expressed by {E_c} =...

i got these vectors R4: v1=(1,1,0,1) v2=(0,-4,2,0) v3=(0,0,-18,0) u1=(1,1,0,1) u2=(-1,0,1,0) in the row reduction process v1 v2 v3 u1 are left independent i need to find the orthogonal base of u+v? in the solution i was told that because v1 v2 v3 u1 are independent then the...

Homework Statement Consider 1L of a solution that is 0.100 M in acetic acid and 0.100 M in sodium acetate. What will the pH be, when 0.0900 mol of sodium acetate are added? Ignore changes in volume. acetic acid pka = 1.75 E-5 Homework Equations HA --> H+ + A- pH=pka +log A-/HA...

Why the base of an electric iron is made thick and heavy?

Hello, I found one excercise - convert a rational number 63/64(base - 10) to a number system with a base of 4 using Radix conversion. Searching throught the internet i found this formula (i hope it`s the correct one :) ) - http://img255.imageshack.us/img255/903/races3.jpg Unlike...

G'day. I was wondering about the possibilities of making a permanent magnet hoverboard that levitates above a permanent magnet floor. They say that these new neodymium magnets can attract hundreds of kilos/pounds. Since repulsion and attraction forces are the same magnitude from what I hear, why...

Homework Statement 3 = Log2x 64 Homework Equations N/a The Attempt at a Solution 3 = Log2x 64 2x3 = 64 x3 = 32 x = Cubic root of 32 x = 3.1748 I'm fairly certain the answer has to be 2 b/c 2x would be equal to 4, and 43 = 64. Anyone mind helping me on this one? Probably...

I did an acid/base titration with acetic acid and sodium hydroxide to determine the concentration of acetic acid present in vinegar but I'm not quite sure how to go about calculating the concentration of it. First things first we dissolved 25ml of vinegar into 250ml of water and filled the...

Homework Statement 800ml sample of 2.00 molar formic acid HCOOH (or HA) ismixed with 200ml of a 4.80 molar NaOH. Calculate the [H3O+] of the resulting solution. Homework Equations (for buffers) pH=pKa-log(HA/A-) Ka for formic acid is 1.8x10-4 pH=14-pOH [H+]=(1.00x10-14)/([OH-) The...

I wish to store thousands of letters onto a computer for a friend. What is the best way to do this? Use Access, or write a program in C/C++ to store and fetch the letters onto CDs. Any suggestions gratefully received, as I have no idea how to get started on this.Thank you very much.

Let's take a simple example. Both a cylinder and Möbius strip consist of a circle with a line segment associated with each point of the circle. The cylinder is considered truly equivalent to the direct product S1 X line segment while the Möbius strip is only locally like S1 X line segment...

In DNA, the base pairs are on the inside of the heli. Eplain why purine-purine and pyrimidine-pyrimidine base pairs do not occur, only purine-pyrimidine base pairs?

specific heat capacity is measured in joule per gram-kelvin (J g–1 K–1). In base units it is m2 s-2 k-1. Is that meaningless to express specific heat capacity in base units? Is there an explanation? Thanks Nick

How the voltage gain of the amplifier depends on the frequency of ac signal. please explain. what is the role of coupling capacitors? how voltage gain is effected in mid , high and low frequency range? thanks.

Homework Statement Ammonia acts as a base in aqueous solution; Kb is equal to 1.8 x 10-5. What is the Ka for the ammonium ion NH4+ in aqueous solution? Homework Equations The Attempt at a Solution I am totally lost for this question, can someone please start me off? all i know...

Homework Statement hello I have to make a concrete base in metres cubed total 1.68 metres cubed. The ratio to concrete is 1 part cement to 2 parts sand and 3 parts gravel. how much cement,gravel, and sand in kilograms? Homework Equations ? The Attempt at a Solution ?

Homework Statement Calculate the pH after 0.030 mol NaOH is added to 1.00 L 0.100 M HC3H5O2 and 0.100 M NaC3H5O2 Homework Equations Ka=[H+][A-]/[HA] pH=-log([H+]) or 14-pOH=ph The Attempt at a Solution HC3H5O2 <-> H+ + C3H5O2- NaC3H5O2 <-> Na+ + C3H5O2- I know that Na+ has no...

Homework Statement Log [with base x]216 =6 Find x Homework Equations The Attempt at a Solution Ok, so I put the log equation into exponential form. It now becomes: x^6=216 I'm lost on what to do next.. I've tried taking the e and ln of both sides, but when I check it, it's...

Suppose for a given matrix A, Sarah finds the eigenvectors v1 = [1 3 4 5]' and v2 = [5 6 3 4]' form a base for eigenspace of labmda = 2. Now suppose Janie finds the eigenvectors v3 = [1 2 2 3]' and v4 = [7 8 7 6]' form a base for eigenspace of lambda = 4. Is Janie's solution compatible with...

Is there a way to calculate multi digit base 10 logs without a calc or tables? eg.. what is ? log (base 10) of 1381.42?? (without a calulator)??

Hello, everyone. I would like to get some concrete examples of the number of distinct bases of k-dimensional vector space W over a finite field F with q elements. The formula for the number of distinct bases of W is ( p 412 Dummit ) (q^k - 1 )(q^k - q)(q^k - q^2)...(q^k - q ^(k-1) ) I...

Question: Decimal (10-nary) expansions of real numbers were defined by special reference to the number 10. Show that the real numbers have b-nary expansions with analogous properties, where b is any integer greater than 1. Attempt at solution: I think if I show that there is a bijective...

I'm writing an exporter for 3d studio max and i want to export skeletal animation. 3D studio max uses a coordinate system that has the X axis going from left to right, the Z Axis going from bottom to top and the Y axis going from front to back. Opengl uses a left handed coordinate system, whilst...

I was wondering if the Golden ratio base (phinary system) has any use somewhere and if arithmetics with it is easy? I programmed a surprisingly simple algorithm to calculate the logarithm yielding digits in base phi using nothing more than 2 multiplications/divisions per result digit. Can it...

Hi All I have a question that I require an answer to. For the above titration, concentration of A-(conjugate base of acid) is the same as concentration of HA at half equivalence. It is at this point that pka=ph of the solution. I agree to this conclusion, but why is the concentration of A-...

I know that logarithms to the base 1 is undefined, due to the reason that: \log_1{x} = \frac{\log_a{x}}{\log_a{1}} And this leads to divison by zero, which is undefined. There was a question in one of my textbooks that asked describe the graph that results if y = \log_1{x}. Is such a graph...

So I was browsing Wikipedia, and I stumbled across this article: http://en.wikipedia.org/wiki/Conway_base_13_function The article claims that the Conway base 13 function, as a function from (0,1) to the reals is a counter example to the converse of the Intermediate Value Theorem (i.e., that for...

the question is simply to determine the [OH-] and pH of a solution that is .210 M in HCO3- first of all if i can get [OH-] then i can easily get pH by converting [OH-] to [H+] and then doing the -log[H+] so that part is easy. i just cannot get [OH-] what i did was first write the...