Resistance Definition and 1000 Threads

Grεετings! :smile: I have some questions about a physics problem. I would appreciate some help with understanding this. Homework Statement The task is to plot some graphs for a projectile at different angles, first when neglecting air resistance and then including a formula for air...

Homework Statement Create a 15V regulated power supply capable of providing a maximum load current of 25 mA. Circuit looks like this: http://i.imgur.com/fMtscbG.png?1ILmax (maximum load resistance) = 25mA Izt (test current) = 20mA Izk (knee current) = 25mA rz = 11 Ω Vz (nominal zener voltage...

Homework Statement If a ball is thrown upwards and lands in the same spot, would it take longer to reach max height or drop back down from the max height? Also use air resistance. Homework Equations The Attempt at a Solution I believe that it would take longer for the object to...

We know that the angle of \(\frac{\pi}{4}\) causes a projectile to travel its max distance when air resistance is neglected. When we consider air resistance is the \(\frac{\pi}{4}\) still the angle that produces the max distance? With air resistance, the projectile with of course travel less...

I'm having trouble with this problem. Any advice would be appreciated. I know I can't group all resistors together in one loop, but I'm not sure where to draw my loops. Should I choose the 200 ohm and 300 ohm for one parallel and the 400 ohm and 80 ohm for the other parallel? I have a...

Homework Statement This isn't exactly homework...but I'm not sure where to post it. I was reading a textbook, and got myself in a mental predicament. I understand the reasons the book gave, but I want to *really* understand. So my question: "Why does air resistance decrease as the...

Homework Statement Homework Equations Parallel-Series resistors combinations. The Attempt at a Solution Using an approach much like the one used to find the Thevinin resistance: 1- Open circuit between A and B (R1, R2, R3), and short circuit the voltage source. 2- (R4//R5)+R6=170 3-...

Homework Statement A cell of unknown e.m.f. , ε , and internal resistance, r, is connected in series with a variable resistor. A voltmeter is then connected across the terminals of the resistor. When the resistor has a value of 16.0 Ω the voltmeter reads 1.20 V. When the resistance is...

X + Y + Z -> A + C+ + B- Initial Concentrations Z= 4.1 X 10^-3M, X=2.3 X 10^-1M, Y= 1.2 X 10^-1 M. http://s121.photobucket.com/user/marykaywest420/media/81386cf6-e132-4578-8fb5-1024a2a3f3d5_zpscc804723.jpg.html?sort=3&o=0 3. So my attempt included graphing -R/(R∞-R) vs. time. which produced...

Homework Statement A circuit is constructed with five resistors and one real battery as shown above right. We model. The real battery as an ideal emf V = 12 V in series with an internal resistance r as shown above left. The values for the resistors are: R1 = R3 = 59 Ω, R4 = R5 = 79 Ω and R2 =...

Homework Statement Given the circuit in the image (with a current source of 2A and several resistors), what's the voltage in R3? http://postimg.org/image/yl6czh9u7/ The answer options are: 1.1V 0.77V 50V 0.55V Homework Equations Ohm's law. V=RI The Attempt at a Solution I...

Homework Statement Does a flashlight battery have internal resistance? Explain. Homework Equations V = ε - Ir The Attempt at a Solution Yes, they do have internal resistance. This results in the open circuit ε being different than the voltage measured across the terminals if a current is...

Homework Statement When a 10 ohm load is placed across the terminals of a battery, the terminal voltage is 11.0V. When a 100 ohm load is used instead, the terminal voltage is 11.9V. What is the internal resistance of the battery? Homework Equations V=IR The Attempt at a Solution...

Sorry for my crude drawings but I thought it was easiest and quickest this way to post the question. Homework Statement Calculate the effective resistance for the circuits below. A. B: Homework Equations R_{series}=\sum\limits_{i=1}^n R_i \\...

Hi, I am fairly new to superconductivity (introductory college level). I have covered and grasped the basics but was wondering if someone could shed some light on what specifically causes materials to have zero resistance when they become superconducting. I know that cooper pairs form when the...

What are the pros/cons of high resistance grounding versus solid grounding and low resistance grounding? What is the preference for different applications? What complications does high resistance grounding introduce in drive system applications? Thank you.

Hi, I am massively confused with what resistance is and how it applies to circuits and would be very grateful if someone could help. I know this sounds like a basic question but I have been reading for hours and the more I read the less it makes sense. My book says that resistance is 'the...

Hello guys, My teacher gave me a question regarding calculation of equivalent resistance, trying to solve which I'm losing my sanity. I feel a bit ashamed because this is my first post and I'm using it to ask a doubt, a little selfish of me. But it's kind of urgent so I don't really have a...

Homework Statement Use resistance reduction and source transformation to find Vx in the circuit below. All resistance values are in ohms. Homework Equations The Attempt at a Solution For this problem, I know I can combine the 16 Ω resistors, but where I'm having a little trouble...

Dear all, I have recently come across a project that requires me to find a device that does the following, A device that: 1)generates "0" movement 2)have a shaft that can be pulled or pushed over a distance 3)I can induce a variable resistance force to the shaft (to counter external...

Homework Statement Determine the equivalent resistance Req as seen by the voltage source VS (the resistance between a and b) http://i.imgur.com/A1ueQnd.jpg Homework Equations Series-Parallel combinations The Attempt at a Solution http://i.imgur.com/K1ItpF0.jpg The only...

I'm trying to find the equivalent resistance of this circuit but I don't know where to start. The solution manual says that the 5 and 20 ohm resistors are in parallel as well as the 6 and 3 ohm resistors. Can someone explain why?

Homework Statement A person gains weight by adding fat - and therefore adding girth - to his body and his limbs, with the amount of muscle remaining constant. How will this affect the electrical resistance of his limbs? a. the resistance will stay the same b. the resistance will...

Homework Statement http://imgur.com/w5AQ1A8 As shown in the image: In the circuit below R1=100Ω, R2=1000Ω, R3=99Ω, R4=1000Ω, R5=10Ω, and V=10V. (a) Relying on the Thevenin theorem, find the equivalent voltage and equivalent resistance for the circuit below when the resistor R5 is taken out...

Homework Statement http://postimg.org/image/p14d9faf9/ The top two resistors are in parallel, so their equivalent resistance is 0.6 ohms. But if you were to draw the equivalent circuit, where do we place this equivalent resistance? can it be placed either where the 1 ohm or 2 ohm...

Gentlemen/Ladies, Long time reader, first time posting. I have a few projects that I would like to get done, and I realized if I don't start getting them done, I never will. Heh. I'm making mistakes calculating the resistors I would need for the following. I've done it 5 times now because each...

Homework Statement Using Ohm's and Kirchoff's Rules find the unknown resistance Rx Homework Equations V = IR Sum of currents at a node is zero Sum of voltages around a loop is zero The Attempt at a Solution For the 2 ohm resistor I found the voltage to be 4V by the formula...

Can some check my answer, please? I only did number 1 because I have no idea how to do number 2. NOTE: Calculators are not allowed, so no need to give the exact value. For example, if the answer has √2, just leave it as √2, instead of writing it as 1.41... Power source voltage e(t) =...

"you know for a fact that a bowling ball drops more quickly than a feather. This is true, but it has nothing to do with gravity. The only reason this occurs is because the earth’s atmosphere provides resistance. " friction??

Homework Statement Okay, So I Have A Physics Packet That My Teacher Handed Out On Inclined Planes. I Was Not There So I Do Not Know How To Complete The Table. I Have To Complete A Chart. The Chart Gives Me The Length Of The Incline, The Height, & The M.A. . I Know How To Calculate The M.A...

(please check attachment) Calculate the effective resistance between A and F Initially, I thought that the first resistance is ignored and the current takes the lower path. Then 2Ω and 2Ω are in parallel giving an effective resistance of 1Ω. However, it could also be that all three are in...

Resistance Of An Unbalanced Wheatstone Bridge Circuit How to find the equivalent resistance across the battery (I mean the whole circuit) of a Wheatstone Bridge circuit IF GALVANOMETER CURRENT IS NOT ZERO (i.e. unbalanced circuit)?

Hi guys I have been playing around with a piece of tungsten wire by supplying it with 12Vdc and measuring the current draw to see how much the resistance changes when the wire is glowing hot. while doing this i am not getting any change in the resistance, the wire has the same resistance when...

Homework Statement What is the equivalent resistance of the infinite resistor chain, shown in the figure, between the points A and B? Plot the equivalent resistance versus q graph. [PLAIN]http://www.komal.hu/kep/abra/e4/b2/0d/cec528140d62b825f84ecf4d8.gif Homework Equations The...

Antibiotic resistance mechanisms etc -- Book Recommendation? Hi, A friend of mine is a biomedical scientist specialising in microbiology. He's interested in antibiotics, so I'd like to buy him a book for his birthday. The trouble is, I haven't a clue what to look for. Is there any book...

Homework Statement how many minimum no of resistances of eash 2Ω resistance can be connected to have an effective resistance of 1.5Ω Homework Equations The Attempt at a Solution I tried to put 2 in parallel,series and different combinations. After 5-10 mins of relentless...

I came up with this problem, and solved for it, but I do question its accuracy, and id like to know how I could make it a better model. (it is not a homework problem) So, a block, of dimensions a (rests on the z axis) by b (rests on the y axis) by c (rests on the x axis), is moving with a...

I know that Cold Air is more dense than the warm air, so for example: If a car was accelerating facing a hot air, it will face less air resistance. But if it was facing a Cold air, it will face more air resistance because the cold air contain more mass per volume for each particle. It will face...

Hi, so I am trying to model the path of a tennis ball when serving. I already have the model without air resistance, but now I'm getting into differential equations with the air resistance. I obtained two differential equations for acceleration that i think are correct, but I'm not sure where to...

Homework Statement Given the following circuit find the input resistance as seen through vo. Homework Equations The Attempt at a Solution To solve this problem I started by drawing the signal equivalent circuit: As we can see the voltage vgs = vi - vo. To find the input resistance I used...

I know that the current should flow through all the circuit but I have heard that the two vertical R in the circuit don't count I can't understand why?! I need a obvious clear explanation for this in detail thanks in advance.

I would like to know the equivalent resistance of this circuit with a clear obvious explanation, thanks in advance

Homework Statement Find the internal resistance seen at Vin. Homework Equations The Attempt at a Solution To solve the problem I started by ignoring the condensators and substituting the MOSFET by it's model. This resulted in the following circuit: By applying...

I am not a physics professional. I have just found an interest in physics on my own. My question is as follows: Imagine a 50 pound weight here on earth. It's mass has a weight of 50 pounds in 1g gravity. This mass, weighing 50 pounds, has a certain amount of resistance to acceleration...

There are two formulas for resistance R=pl/A V=IR What is the difference between them? Question b on the sheet. Why can you not use that data to calculate current flow when connected to a power source. I suspect it has something to Do with the difference between these two formulas.

My textbook source is: Fundamentals of Physics, 6th edition, by Halliday, Resnick, Walker According to Newton's well known 2nd Law of Motion: Fnet = ma In chapter 2, in the case of free fall, the Fgrav = mg, where g = -9.8 m/s2, assuming that movement along the axis of y is positive...

I got this question ( i won't include a lot of details because this is not the homework forum) where i need to calculate the power dissipation due to internal resistance. What i did is , i calculated total V and total R and I , then i treated the battery as a normal resistance ( eg. a 1kohm...

i am confused at the 20v voltage since it becomes short circuit.i had started reading the circuit from the left side 1M ohm and 2k ohm are in parallel and in series with the 3k.knowing that current wants less resistant ways it will go to the killed voltage source...after that I am wasnt able to...

Hi everyone, I have attached an image of the op-amp configuration (all op-amps are ideal). Basically, the question asks to calculate the resistance seen through the voltage source. The answer is 3 kΩ but I just don't understand how this is found. If someone could assist me, I would really...

Homework Statement I have to find the ratio of RB/RA where R is electrical resistance. Both objects A and B have circular cross section and length L, and are made of the same material. A has radius r0. B has radius r0/2 at the bottom and increases linearly to 2r0. Homework Equations...