Resistance Definition and 1000 Threads

Homework Statement Given this following circuit: What is the internal resistance of the meter movement ( R_I). This is part of a project I'm doing and I know the equation that gives you the internal resistance in this circuit. $$R_I = \frac{R_sR_p}{R_s - R_p}$$. However, I have no idea how...

I heated two different materials with a laser beam for about 10 seconds and these are the measured temperature profiles: From the various solutions to the general heat conduction equation, temperature rise seems to increase with increasing thermal resistance of the material. The total...

Homework Statement A 2 kg ball (k factor of 0.02 m-1) is in free fall. The initial downward velocity of the ball is 12 m/s. Find the difference in displacement after 1s both with and without air resistance. Homework Equations vf = vi + at y = yi + 1/2(vi+vf)t y - yi = vit + (1/2)At2 - (1/3)Bt3...

Generally, a material is metal or insulator is simply determined by the gap. But if we view it in another way, to measure the resistance in different direction, says x and y, and there are usually different. And then measure the resistance change with temperature. Usually, the resistances goes...

If you have wire that has 100 ampere current but your load is only 0.5 ampere.. how come the load won't be destroyed by the powerful 100 ampere source? Or let's take the case of hose. If you have water running so fast inside a 10 inches diameter hose.. and you put a small hose between it.. the...

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...

What is the resistance of Device Q when a current of 200mA flows through it? Wouldn't the resistance of the device be approaching 0 Ω as its characteristic resembles one of a diode (gradient = 1/R)? Apparently, the answer is just using V = I R, and solving for the resistance. Is there...

I started an electronics program recently and I am a month into it so I am quite new at this. I have a problem involving a potentiometer and I don't understand how to compute the voltages because I don't know what I am supposed to use for my resistance values. I know that in series the total...

In this circuit,first there will be voltage drop in the internal resistance of the voltage source.Mostly,the voltage source is assumed ideal in circuits,however,here a practical voltage source is assumed. So,there will be voltage drop in the internal resistance of the voltage source which will...

1. Homework Statement How to determine the change of R of a non-ohmic conductor from different parts of I-V graph? Please see the sketch attached. Homework Equations R=V/I The Attempt at a Solution For the part that passes through the origin, it is obvious that the...

I was wondering that if rolling resistance is basically caused by slight deformation of a body, we must have formulas in place to relate it to the physical and material properties of a body. But when I went ravaging for it in library or internet, everything was experimental. I wished to know...

Hi, We're studying Contact resistance and the professor has given assignments on contact resistance. But I can't find any books to refer to. Here is one sample question: The books I'm referring to are ones by Donald Neaman, SMZ, Kanos. but none of them have any mention of 1-d or 2-d model for...

Homework Statement If the circuit of parallel and series resistors , is as follows , what's the equivalent resistance for the group? Homework Equations neglecting the battery internal resistance... irrelevant to the question. The Attempt at a Solution I tried to do the following R1=8+12=20...

In lower-division physics classes, air resistance is usually ignored to make the mathematics of projectile motion easier to understand. When air resistance is included, it's often stated that at lower velocities, air resistance is proportional to the velocity of the object, Fair ∝ kv At...

We have two identical balls sitting at the same height. One of them is released without applying any force (it falls freely) and the other one is given a non-zero horizontal velocity. Which of them will hit the ground first? The force of air resistance is proportional to the square of the...

I am trying to calculate the correct component values to use in a simple series LC filter, however I am not sure which value of resistance is to be included in these equations. When talking about a series LC filter, is the resistance required for calculating q factor the resistance of the...

Homework Statement A battery has an emf of V and an internal resistance of r. What resistance R, when connected across the terminals of this battery, will cause the terminal voltage of the battery to be ? A. r= R B. R= 4r C. R= r/4 Homework Equations V=IRThe Attempt at a Solution Req= r+R =...

Homework Statement The problem and its solution are attached. Homework Equations "Steps to follow for Thevenin’s Theorem: (1) Find the Thevenin source voltage by removing the load resistor from the original circuit and calculating voltage across the open connection points where the load...

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...

Homework Statement This graph was given, which describes the current through a resistor, as a function of the voltage. Then, we were supposed to find the resistance of the resistor when 3V<V<5V. But it changes throughout this range, doesn't it? Because in the answers (Mind you, this is the...

Homework Statement Find the combined resistance once the switch is closed. Homework Equations V=IR The Attempt at a Solution I tried applying Kirchoff’s law but I got many equations, I am sure there is a more efficient way. I also tried to re-draw the circuit, but wasn't sure how to do so...

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 the...

Hello all, I want to say thank you in advance for any and all advice on my question. My classical mechanics textbook (Marion Thornton) has been taking me through motion for a particle with retarding forces. The example it keeps giving is: m dv/dt = -kmv which can be solved for: v = v0e-kt...

Homework Statement I came across a question asking " which one of these circuits has the largest resistance to the current? Homework EquationsThe Attempt at a Solution * In A the positive terminal of the battery is connected to the p-type region and the negative one to the n-type region...

I"ve seen several texts that say something like this: Our equation of motion along x is dvx/dt = -g(vx/vt) Integrating this, we obtain equation 178 at this link (pretty near the top; sorry, but I can't figure out how to put the equation here). It's from FitzPatrick's online notes for...

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...

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...

Homework Statement When the defibrillation shock is applied, the capacitor discharges through the patient as shown in the diagram below: The fraction of charge remaining on the capacitor 1.00 ms after it begins discharging is 0.300. Calculate the resistance of the patient. Note: This will...

Complete question: Will flow ever reverse or stop if we increase resistance in this pipe scenario? There are 2 comunicating vessels. The highest vessel is coninuosly alimented with new water. Water in excess flows down on the sides. Water will try to reach the same height in both vessels, so...

Homework Statement https://imgur.com/a/XD3Km4t I'm trying to find the thevenin equivalent resistance across the opened terminals. Homework Equations I know you short circuit the voltage source and do simple circuit analysis, however I'm getting confused in determining what resistors are...

Hello, I am currently doing research on the aerodynamic properties of a rotating cylinder in a cylindrical housing. The cylinder represents a rotor in a electric motor. The air gap between rotor and stator is about 0.5mm. I'm looking for a theoretical analysis and calculation on the...

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. Homework Equations Req for parallel = 1/R1 + 1/R2 + ... Req for series = R1 + R2 + ... The...

Homework Statement I'm asked to find the voltage, current, and resistance through each resistor in the given circuit. Homework Equations Req for parallel = 1/R1 + 1/R2 + ... Req for series = R1 + R2 + ... The Attempt at a Solution First, I want to find the total resistance in the circuit...

Homework Statement Homework Equations ρl = RA A = π r2 The Attempt at a Solution l = RA (ρ is constant) A1 = π (D/2)2 = (πD2)/4 A2 =π (2D/2)2 = πD2 = A1 /4 l2 = 2*l1 ##R=\frac{l}{A}## R2 = (2l1)/(A1/4) = 8 l /A = 8R1 Could someone tell me where is my mistake ?

Homework Statement Calculate the magnitudes and directions of the currents in each of the 3 resistors in the circuit above, if... (a) ...both batteries have zero internal resistance. (b) ...each battery has an internal resistance of 1.0 Ω. Homework Equations I1 = I2 + I3 (Node Law)The...

< 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...

Homework Statement Homework EquationsThe Attempt at a Solution From symmetry , C and D are at the same potential . So , resistance between them can be removed . This leaves us with three parallel branches between A and B i.e 45 Ω || 45 Ω || 15Ω . The net resistance will be 9 Ω . But this...

Homework Statement Three identical batteries are first connected in parallel to a resistor. The power dissipated by the resistor is measured to be P. After that, the batteries are connected to the same resistor in series and the dissipated power is measured to be 4P (four times larger than for...

I'm currently developing a heat sink for a product that produces up to 150 W max power dissipation. I'm currently getting a negative thermal resistance for the heat sink. I don't think that is possible.. I'm not sure how to move on at this point to properly design a heat sink to meet the heat...

I'm currently doing a heat sink calculation design and having a little confused moment with the area of the chip with a AuSn (Gold Tin Solder) pre-cut that's attached to the bottom of the chip. I've tried looking around online for AuSn's thermal resistance value, but there is none besides a...

Homework Statement Consider the electric circuit shown in the figure. Assume that V = 13.7 V, R1 = R2 = R3 = R4 = R5 = 7.00 Ω. What is the equivalent resistance of the circuit? Homework Equations total voltage of a series circuit is the sum of the voltage of all the resistors total current of...

Homework Statement A coaxial cable consists of a core cylindrical wire and a coaxial cylindrical shell, as illustrated in the Figure below. Consider a cable made of copper, which has resistivity of ρ=1.70×10−8Ω·m. Thecorewirehasaradiusof r =1.0mm. Theinnerradiusofthe 1 outer shell is r = 5.0...

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? Homework Equations First, I tried to solve this like this...

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...

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...

Hi everyone, I was wondering how to best calculate the breakage resistance of a drill hole which is being flowed through with a certain volumetric throughput within a polycarbonate (PC) rectangular plate. Well basically, the breakage resistance of the PC around the drill hole :) The plate is...

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 =...

Homework Statement Homework EquationsThe Attempt at a Solution [/B] The circuit is symmetric about AC and BD , but I am not sure how to use this to simplify the circuit . Could someone help me in solving this circuit using symmetry considerations .

Homework Statement Homework EquationsThe Attempt at a Solution I am trying to solve this question by symmetry .If I draw a line perpendicular to the line joining AB then points C and D are symmetric . Now I am unsure how to proceed further .

Dears, Please help me out with this. The attached figure is an equivalent circuit of an induction machine. I'm trying to find the current (Is). It's assumed that the core losses are neglected and hence Rc =0. If this is the case, then Rc (short-circuited) is in parallel with jXm. What's the...