Resistance Definition and 1000 Threads

Homework Statement We were given five samples of nichrome wire, each with a different diameter but the same length. A micrometer was used to measure the diameters. We then measured and recorded the electrical resistance, R in Ohms of each nichrome sample with a DMM. I will try to summarize all...

Homework Statement Assuming the wires have negligible resistance, find the equivalent resistance between the terminals A and B. Answer to 2 significant figures. Homework Equations [/B] 1/R = 1/R1 + 1/R2 ... + 1/Rn R = R1 + R2 + RnThe Attempt at a Solution [/B] I have drawn a more...

Using the regression eqn. Find the base resistance of the thermistor. Find the temp. Of the boiling water using this eqn. Y=1.54e^-0.059x How do I go about solving this problem

How exactly do you tell if two elements are in series or parallel? I know that if two elements share two of the same extraordinary nodes then they are in parallel: But in this example I do not see that. I know for certain that the answer for Rt is: [ ( (R1 || R2) + R3) || R4 ] + R5

Hi. Consider a simple circuit consisting of a voltage source ##U## and a load with resistance ##R##, e.g. a lamp or a motor. The current is given by ##I=U/R##. The number of electrons passing the circuit per second is ##n=I/e##. The power consumed by the load is calculated by $$P=U\cdot...

Homework Statement Suppose you want to run some apparatus that is 95 m from an electric outlet. Each of the wires connecting your apparatus to the 120 V source has a resistance per unit length of 0.0065 Ω/m. If your apparatus draws 2.9 A, what will be the voltage drop across the connecting...

As you know, resistance of a rectangular shape is given by R=ρ A/L But how do we theoretically calculate the resistance of the bottom case? ( now, the current flow is not parrallel, current flows from bottom through the right side) I would like to know if there is any references for this...

Homework Statement Twelve identical wires, each with resistance R = 1.0 ohms, are linked together to form a octahedron. Find the resistance in an octahedron between opposite vertices and adjacent vertices( A,B for example) picture 2. The attempt at a solution I already found the resistance...

Hello everyone, From what i know electrical resistance for metals is a constant, but in fact it varies with temperature but not voltage. Explanation for metals and temperature is something like "heat, which is in fact average speed of electrons, does obstruct tranmission of other electrons...

In an open circuit, a voltmeter in parallel to a battery measures the EMF. Once the circuit is closed, the measured voltage drops due to both the internal and the external resistance. My question is how can the initial resistor not affect the voltage the voltmeter measures? Additionally...

Homework Statement So we are doing an experiment where we are trying to place a 60W light bulb in a room. It is connected to the mains power supply, but we are imagining that it is DC instead of AC. Now we have to make sure that we only loose 0.1% of power in the wires. Homework Equations P=VI...

Homework Statement Find total Resistance Homework Equations 1/Req= (1/R1)+(1/R2)... The Attempt at a Solution Can someone please explain me how 5 ohm R and 3ohm R are in series and then in parallel with the 2ohm R? Thanks

Homework Statement Determine the resistance of wire at room temperature and at the melting point of the given material. GIVEN: Material = Aluminum Diameter of wire ##= 0.5 mm = 5.0 * 10^{-4} m## Length of wire ## = 0.5 m = 5.0 * 10^{-1} m## Temperature Coefficient: ##\alpha = 3.9 *...

Hey, I am having problems with this. I need help with these 2 circuits I am basically lost and not sure how to start. I need to find voltage, current and potency on each resistance help would be much appreciated, thank you http://imgur.com/trm1On0 http://imgur.com/a/KD3zr

Homework Statement A 12 V, 24 W lamp and a resistor of fixed value are connected in some way inside a box with two external terminals. In order to discover the circuit arrangement inside the box a student connects a variable DC power source and an ammeter in series with the box and obtains the...

Homework Statement You have a 9V battery with an internal resistance of 1.5 ohms. If a 3 ohms load is connected to the battery, how much current will flow through it? When the 3 ohms load is connected, what potential difference will an ideal voltmeter read across the battery's terminals...

Hi, I am trying to find out series and shunt resistance of solar cell from I-V curve which starts from Isc and going to Voc. I read some papers and for single illumination mostly said Rs= -(dv/dI)V=Voc and Rsh= -(dv/dI)I=Isc. so I am finidng Rs from slope between points from Vmax to Voc, and...

Homework Statement A bulb is used in a torch which is powered by two identical cells in series each of EMF 1.5 V. The bulb then dissipates power at the rate of 625 mW and the PD across the bulb is 2.5 V. Calculate (i) the internal reistance of each cell and (ii) the energy dissipated in each...

Homework Statement I have a square conducting loop of size L that contains two identical lightbulbs 1 and 2. The magnetic field that goes into the page varies B(t) = a*t + b. Lightbulbs have resistance of R0 Here is a question and the sample response. Disregard the part of the question that...

Homework Statement A battery of EMF 12.6 V and internal resistance 0.1 Ω is being charged from a DC source of EMF 24.0 V and internal resistance 1.0 Ω using the circuit shown in the figure below. V1 and V2 are high resistance voltmeters and R is a fixed resistor. (a) What is the polarity of...

Homework Statement The battery in the circuit below has EMF 5.4 V and drives a current of 0.30 A through a lamp. The voltmeter reading is 4.8 V. Explain why the voltmeter reading is less than the EMF of the cell. Calculate values for (a) the internal resistance of the battery, and (b) the...

Homework Statement A battery is known to have an EMF of 5.0 V but when a certain voltmeter is connected to it the reading is 4.9 V. The battery can deliver a current of 0.40 A when connected to a resistance of 12 Ω. What is the resistance of the voltmeter? Answer: 24.5 Ω. 2. The attempt at a...

Homework Statement A battery of internal resistance 0.50 Ω is connected (as shown below) through a switch S to a resistor X, which is initially at 0 °C. When S is closed, the voltmeter reading falls immediated from 12.0 V to 10.0 V. The reading then rises gradually to a steady value of 10.5 V...

Homework Statement When a particular voltmeter of fixed resistance R, which is known to be accurately calibrated, is placed across the 1.8 kΩ resistor in the diagram below it reads 2.95 V. When placed across the 4.7 kΩ resistor it reads 7.70 V. (i) Why do these two readings not add up to 12 V...

Homework Statement A semiconductor diode and a resistor of constant resistance are connected in some way inside a box having two external terminals, as shown in the diagram below. When potential difference of 1.0 V is applied across the terminals the ammeter reads 25 mA. If the same potential...

Homework Statement Calculate the resistance of the network shown below: (a) between A and B, (b) between A and C. Answers: (a) 3 Ω, (b) 4 Ω 2. The attempt at a solution (a) I would say that the resistance is 4 Ω between A and B. (b) For A and C the resistance is: (1/4 + 1/4)-1 = 2 Ω. In...

Homework Statement Find the resistance for an incomplete circuit. Homework Equations V = IR The Attempt at a Solution The resistance would be infinite because no current can flow.

Homework Statement I'm studying for a test and since this is technically a textbook problem I figured I'd post here to prevent being flagged. I have the circuit redrawn. Homework Equations Series: Req = R1+R2... Parallel: 1/Req= 1/R1 + 1/R2... The Attempt at a Solution I want to understand...

Homework Statement I have a circuit with a diode in it. I have to find the thevenin equivalent in order to reduce the circuit to a DC source, single resistor and single diode. How do I account for a diode when trying to find Rth and Vth? Do I just remove it and have it act as a short circuit or...

Homework Statement Find the equivalent resistance of the circuit shown, for circuit 3.7b, the one in the upper right : https://scontent-ort2-1.xx.fbcdn.net/v/t34.0-12/14429160_641550399338143_303002326_n.png?oh=ad8d346cfcaff147c9cd7a9d2b509411&oe=57E6C47C Homework Equations Rseries=Rtotal...

Homework Statement Design a voltage divider circuit to provide an output voltage v0 = 5V from a 12V source. The current taken from the 12V source is to be 100mA. a)Find the values of R1 and R2. b)Now suppose a load resistance of 200 ohms is connected across the output terminals (in parallel...

Hello guys, Can someone guide me through this problems solution? I need to find the Thevenin's Equivallent for this circuit, between A and B. I'm terrible at Circuits and I'm eager for some motivation and help. Thanks a lot in advance.

Homework Statement We conducted experiments using copper wires to observe the effect length has on resistance. We measured lengths from 5 - 30 cm and used a multimeter to measure the voltage while supplying a constant current from a power supply package. The multimeter measures in mV. Plotting...

Hello! I am bit confused about kirchhoffs law with capacitors. So if I have a battery and resistance, I obtain V-RI=0. But from what I read, if I have a capacitor and resistance (so discharging capacitor), the equation reads R(dq/dt) + q/c = 0, which is equivalent to RI + q/c =0. Why in this...

http://imageshack.com/a/img923/733/FJKAqj.jpg so here is the deal. is rolling resistance N+Ft or are they "separate" in a means of: N part is for static friction = mu*N and Ft is part of rolling resitance=coefficient of rolling resistance*Ft so that in order for tire to start rolling without...

Homework Statement Solve the differential equation ##\displaystyle Cv^2 - mg = m\frac{d^2 y}{dt^2}## Homework EquationsThe Attempt at a Solution The problem is nonlinear, so we need to use unconventional methods. Specifically, if we can express the derivative of y with respect to v, then we...

From, https://www.sciencenews.org/article/scientists-watch-bacteria-evolve-antibiotic-resistance For bacteria, practice makes perfect: Adjusting to ever higher levels of antibiotics preps them to morph into super resistant strains, and scientists can now watch it happen. A new device — a huge...

how to find a hollow cuboid's resistance between two points on same face but not lying on the edges. the line joining 2 points is parallel to the length of the cuboid. resistivity is uniform another related doubt - will resistance between those same points change if the cuboid is deformed (the...

Here is an image with information: https://i.snag.gy/UMCRig.jpg I have calculated the total power dissipation as 11W. What I don't see is why R1 has a higher dissipation rate than R2/R3, and my main question is how do I calculate the power dissipation of R1? I get that R2/R3 are in series so...

Homework Statement I am trying to calculate the power of Rload in the circuit attached (SEE ATTACHED CIRCUIT). The coupler I am trying to model is the Agilent 778D. Can someone verify that I calculate this out correctly? Homework Equations y dB = 10 * log10(x) V = i * R P = v * i The Attempt...

I think this is the place to ask these questions about static resistance of semiconductors: The static resistance in semiconductors is that kind of resistance that will decrease if the semiconductor is more heavily doped, right? In transistors, and especialy saturated transistors the usual 0,2V...

Hey everyone. I thought about this problem the other day, but I don't know what theory I need to solve this problem. Given a 2D rectangle with a known, varying resistance, and a known voltage drop across the length, how would one calculate the current density at each point on the surface. By...

Homework Statement Here: http://imgur.com/a/5rRgu 2. Homework Equations V=IR The Attempt at a Solution Basically from reversing the polarity of the cell and looking at a mirror image of the circuit i got the following relationships. First I(9)=0 then I(1)=-I(4) I(5)=-I(6) I(7)=-I(8). I...

Note: I have come up with a solution myself, but I am trying to understand a different approach to the problem. My textbook solves it in a different manner, and I am having trouble following along. Homework Statement The last part of the problem "determine R1 and R2 such that Rin = 200k". I am...

Hi, I have following two parameters with me a) Maximum three phase fault current in amperes (A) and phase angle in degrees (B). I want to calculate the positive sequence resistance (R) and reactance (X) from above two variables for a symmetric system. I couldn't figure out a way to find R and...

I'm studying semiconductors and i might need a little help with some questions: First the dynamic resistance is the internal resistance of the diodes , but it's called dynamic because it isn't constant, right? Does all semiconductors, pure and doped, have internal/dynamic resistance? The...

I am trying to estimate the amount of electrical power needed to heat up a material from 20C to 1000C in 20 seconds. Assuming it is 18sqin and 3mm thick, I used the specific heat which was given as 0.78 J/gC and weight 11.39g (from the destiny of 3.26). 0.78 J/gC x 11.39g x (1000C - 20C) /...

Hoping this is a simple question for people in the EE field... I study math, so I need some help in the real world (haha). I'm working on a project car that I'm trying to build over the summer, and I'm putting aftermarket gauges in it. Here is my issue. My factory fuel sending unit has a...

Homework Statement See image attached. I am currently stuck on part b. Homework Equations (Rt) (Rint) / Rt + (Rint) The Attempt at a Solution I thought that Rt would be 26.7 kohms, but my answer is not matching up with the answer in the book. I am unsure why since the resistors are in...

Hi all. In a project I'm working on I'm needing to model a DC circuit to find the required power sources/storage to keep the system voltages up to a sufficient level. There's a solar cell array, a reversible fuel cell stack, various DC "appliance" loads, and wire runs with resistances. I dug...