# resistance

1. ### Maximum power in this resistor circuit

My attempt-: So the resistance is coming to be negative.Can anyone tell me my mistake.Thanks.
2. ### I Resistance of composite material

Composite materials consist of various components such as moist wood ,how will the internal resistance of this material behave? If I want to study the resistance of composite materials, which topic should I study?
3. ### Joule heating effect - qualitative explanation

Hi, I understand mathematically why using low resistance results in a greater heating effect. Could someone give an intuitive and microscopic picture of why the current contributes more to a greater power dissipation by the resistor rather than the resistance contribution to the power...
4. ### How to estimate a constant drag coefficient of a boat?

Hi there, I have modelled with MAXSURF a few variations of a prehistoric logboat in order to test a few theories. Now, I am trying to look at resistance-performance over a range of speed. To do so, I need to include a constant drag coefficient without knowing the drag force and velocity (both...
5. ### Calculate the total resistance by integration using the conductivity equation

(i) Dividing the rod into thicknesses of dx we get discs of area A with lengths=dx so using (****) we have the resistance of a typical disc (between point x' and x'+dx) as: (1) $R(x'dx)=\frac{dx}{g(x)A}$ (ii) Using (1) and (*) and the integrating from a to b of the entire rod we get...
6. ### Resistors in Parallel or Series?

Given that they're all on the same branch, I had assumed that they were in series with one another. But with the middle resistor having being on the middle of three branches, it looks parallel. Like I said, I have a feeling it's in series (making the answer 3R). This question is from a past...
7. ### Engineering Help me finding the current in here please (Circuit analysis)

Hi! I've been struggling with this. Original exercise here: Find the value of Iy when R=0. And the value of Vx when R is infinite. For the first part of the question I did this since R=0: I've tried to solve this circuit and I get that Iy and I5 are 0 A, and this can't be possible since Iy...
8. ### I How to solve a complex equation to get the current?

I was reading The Feynman Lectures on physics http://www.feynmanlectures.caltech.edu/I_23.html chapter 23, section 4. In it he derives the equation for current when inductor, resistor and capacitor is connected in series with an alternating voltage source, he derives this equation:-...
9. ### B How a Secondary Resistor affects the Transformer Primary Side?

Let's assume a 2:1 transformer which has a 100V Source connected on the primary circuit and has no/negligible resistance, on the secondary circuit a 5 Ohms resistor is connected. Using the 'Impedance Transfer/Reflection' method, the primary circuit would act as if there was a 25 Ohms resistor...
10. ### A few questions concerning voltage, current and resistance

[ mentor note: post adjusted to conform to hw template and some spellings fixed ] 1. The Problem I have some few questions that connect voltage, current and resistance. Imagine that we have a circuit that consists of a battery (5V), 2 resistors. Now once we close the circuit, battery would do...
11. ### RC Circuit - Rate energy is dissipated in the resistor

1. Homework Statement 1. A 2.01 uFcapacitor that is initially uncharged is connected in series with a 6.51 kΩ resistor and an emf source with 74.6 V and negligible internal resistance. The circuit is completed at t = 0. a) Just after the circuit is completed, what is the rate at which...
12. ### I Effective Resistance (Fluid Mechanics)

Imagine you have a vertical pressure head 2m tall with water flowing down to height 0m and emptying. Through this length we have 3 identical tubes of resistance R and length L. Assuming I know the volumetric flow rate(Q) as a function of height, how can I calculate the resistance of each tube...
13. ### I Power waste (conceptual doubt)

I'm currently in a undergrad level course of eletromagnetism and my professor found it useful to remember quickly of some relationships that we see in high scool, among them power waste. I got the formulas, since they're simple and are direct derivated from the definitions of electric current...
14. ### Explaining a signal converting circuit

i have a drawing of a circuit that converts a signal in range [-5,5] V to a range [0,1.2]V . i wish to understand how it works.. i have basic knowledge of electricity as an undergraduate in general physics but a bit rusty , thus i am here looking for answers...
15. ### Ohmic Resistance and Logic gates

Is ohmic resistance a "necessary evil" in order for transistors to be able to function as logic gates? I mean, I have seen some circuits for the NAND gate in RTL and TTL and they both seem to involve ohmic resistances. Can we make a super conducting NAND gate that will have total ohmic...
16. ### Find the resistance and EMF in a circuit

1. Homework Statement translation ; we know the values of R1 = 1 ohm R2= 2 ohm R3= 6 ohm R4= 2 ohm R5= 4 ohm R6= 4 ohm we can also see the voltmeter reading a potential difference value of 8 volts , and...
17. ### B Is there a relationship between voltage and resistance?

I was getting a bit confused with Ohm's law, and the relationship between the current, resistance and voltage/potential difference? From my understanding, current and voltage both increase or decrease together, while current and resistance do the opposite? I was then wondering if there was any...
18. ### B Electromagnetic coil and capacitors vs resistance

I'm not really sure if this is even scientific but while calculating how much energy is stored in electromagnetic coils and capacitors, pretty much the same formula is used: For electromagnetic coils it's U=0.5LI2 For capacitors it's U=0.5CV2 Why I think they're the same is that in a sense L to...
19. ### Parallel and Series Circuit

1. Homework Statement I'm asked to find a combination of resistors (parallel and/or series) that uses resistors of 25 Ω, 100 Ω, 50 Ω, and 50 Ω. They should add up to give a total resistance of 62.5 Ω. 2. Homework Equations Req for parallel = 1/R1 + 1/R2 + ... Req for series = R1 + R2 + ...
20. ### Voltage, Current, and Resistance Calculations

1. Homework Statement I'm asked to find the voltage, current, and resistance through each resistor in the given circuit. 2. Homework Equations Req for parallel = 1/R1 + 1/R2 + ... Req for series = R1 + R2 + ... 3. The Attempt at a Solution First, I want to find the total resistance in...
21. ### Yenka simulator to build an RS flip-flop

< Mentor Note -- thread moved to HH from the technical forums, so no HH Template is shown > a) Using the Yenka (or similar) simulator, you are required to build an RS flip-flop using 2 NAND gates, switches, LEDs and 330Ω resistors. Test the circuit and prove its correct operation against the...
22. ### Resistance of Coaxial cable

1. Homework Statement Coaxial cable has radius a of copper core and radius b of copper shield. Between there is an isolator with specific resistance ζ. What is the resistance of this cable with length L between the core and the shield? 2. Homework Equations First, I tried to solve this like...
23. ### Current Dividing in an Electrical Circuit

A circuit contains a 7.5V d.c power supply and three resistors. The total resistance of the circuit is 30 ohms. Why will the largest current in the 18 ohm resistor? As far as I know is that the smallest current will be in 60 ohm resistor because it has the maximum resistance. Please explain...
24. ### Understanding voltage dividers

Hi! I'm working on a project in which a small microcontroller with a max. analog input of 5v takes readings from multiple sensors. I would like to make this input window a bit more versatile, and turned to voltage dividers as a solution. 'Problem is, I'm having a bit of trouble understanding how...
25. ### Calculating the conductivity of a solution of HCl and HAc

1. Homework Statement I need to calculate the specific conductivity k and the resistance R of a cell containitng 0.01 M HCl and 0.1 M acetic acid (HAc). I know the molar conductivity of HAc: Λm = k/c = 5.14 cm2S/mol. I also know Ka (HAc) = 1.795 *10-5. I know the cell constant Kcell = R*k =...
26. ### How to find speed with Faraday's law

1. Homework Statement A metal rod can slide on a rail without any friction in the presence of uniform magnetic field of B=1T which is perpendicular to the plane of the paper.The distance between the tracks is d=0.1m and the resistance given is R=0.1 ohm.The resistance of the rail is negligible...
27. ### 10% resistance boundary

1. Homework Statement if someone could help me with this it would be much appreciated. In physics, I used a 98Ω resistor in a series circuit and measured the current and voltage output from battery, using the current and voltage I calculated the resistance. I=0.0094A V=1 Rt=1/0.0094=106.38Ω...
28. ### How to find the power consumed by the light bulb

1. Homework Statement (Is the image read-able now? ) The fig 1 shows the relationship between voltage and current when voltage is applied to a certain light bulb. Next, in fig 2, the bulb is connected in series with a 12-V battery and a 5 ohm resistor. Question : what is the amount of power...
29. ### Resistance of a tungsten filament bulb at 20 C

I was looking for any credible sources who could reveal the resistance of a normal tungsten filament bulb at room temp 20 C? I heard its cold resistance is about 9.5ohms. Is that the resistance at rtp? Thanks a lot in advance!!!!
30. ### Calculating Resistance

Hello! I've took a course about Electrical circuits and Networks at the university, and i found out a problem which is uploaded by my professor, and i think he made a mistake! this is the solution i think that the equivalent resistances are wrong (beside Rab), for example if you look at...