Resistance Definition and 1000 Threads

`After a charge carrier loses kinetic energy in a such a collision, the force due to the pd across the material accelerates it until it collides with another positive ion.' I got this from a book, can someone explain this in a simplest way.

Homework Statement a) find the equivalent resistance of the circuit below b) each current in the circuit c) the potential difference across each resistor d the power dissipated by each resistor. Homework Equations V=IR R=(1/R)^-1 The Attempt at a Solution Not sure if I did the resistance...

Homework Statement Rank the resistors according to to the rate at which energy is dissipated in them. Homework Equations P = I2R P = V2/R Iin=Iout at a node The Attempt at a Solution First I looked considered the 20 Ω (top) and the 10 Ω(bottom). The current in them would be the same, so...

I've been using the following equation for thermal resistance to make basic calculations for a few different engineering designs: $$R_t = \frac{L}{kA} $$ Where L is the resistance path length, A is the cross-sectional area perpendicular to this path and k is the thermal conductivity of the...

Homework Statement initial problem: A 228 −Ω resistor and a 586 −Ω resistor are connected in series across a 90.0−V line. A voltmeter connected across the 228 −Ω resistor reads 24.0 V . Find the voltmeter resistance. For Req, i got Req=228R/(2+228), R being the resistance of the voltmeter. But...

Do transistors give a certain resistance? If so how do you find this resistance? Say Hypothetically for the following example. Refer to (fig.1). The resistor's value is 100Ω, source is 3V. Say if the transistor wasn't there, the amp would be 0.03A or 30mA. But when I run this in a simulation...

Homework Statement Two 1.80 V batteries—with their positive terminals in the same direction—are inserted in series into the barrel of a flashlight. One battery has an internal resistance of R1 = 0.280Ω, the other an internal resistance of R2 = 0.155Ω. When the switch is closed, a current of...

Homework Statement How does emf relate to current, electrical potential, and resistance? Specifically, in the context of the equations I have posted below. Homework Equations V = IR [/B]where V is electric potential, I is current, and R is resistance. V = emf - IR How can V = emf - IR...

I was shown electrolycra recently and initially as you stretch it the resistance increases, which I think is due to the silver in the lycra not being able to shortcircuit as the lycra separates out. However if you keep stretching the electrolycra eventually you reach a critical point at which...

Homework Statement A triple glazed window consists of 3 clear glass panes of 3 mm thickness each, separated by air cavities of 12 mm each. The window area is 1.0 m2 . If the thermal conductivity of the glass panes is 0.8 W•m-1•K-1 and of the air cavities is 0.028 W•m-1•K-1 what is the total...

Homework Statement Three resistors are connected in series to a battery. The resistances are R1 = 15 Ω ,R2 = 25 Ω , and R3 = 30 Ω and the current through the 15-Ω, resistor is 2.7 A . What is the potential difference across the battery terminals if the battery is ideal? What is the potential...

Homework Statement I have to calculate the current through each branch - I1, I2 and I3. Homework EquationsThe Attempt at a Solution The only reason I'm having trouble with this problem is because the voltage source is in the middle and I'm a little confused. I am struggling even to add up the...

I need a variable AC attenuator and the only thing I can think of is an LDR. However I would need the on resistance to be very low, less than 10 ohms. I've only found LDRs with on resistances of 100ohms minimum. Is it possible to go lower than the listed minimum is I use a really really bright...

Hi, I cannot solve for the function g(t) (eq. 6) in the attached figure where there are two series resistances. My solution is incomplete. I do not know how to use Vx in this solution, which is needed because it contains h(t) found in the solution.

Hi! I am having a little trouble with a question asked by a colleague. There’s a ball B with a certain mass M, at rest. A small ball A of mass m is moving with speed v toward M. If m=M, and the collision is perfectly elastic and the two objects perfectly rigid, than we know that A would come...

Hello, I have a question about using the properties of conservation of angular momentum to provide mechanical resistance. Basically, I'd like to create a device that spins a disk similar to a gyroscope. The device has an external input that, depending on the configured orientation of the disk...

Homework Statement I'm having trouble trying to find equivalent resistance. Here's a picture of some circuits I am trying to simplify (http://puu.sh/ngjMC/38160c3464.png) For example, in circuit a, I can see that the 84 ohm and 105 ohm resistor are in series, and that can be simplified, but...

Homework Statement [/B] https://wcl.unr.edu/bbcswebdav/pid-634340-dt-content-rid-2875167_1/xid-2875167_1 So I am given the above image, and I am told to calculate the voltage in the circuit. Homework Equations V = IR R_net = (1/R_1 + 1/R_2 + ... + 1/R_n)^-1 for parallel resistors 3. The...

I have voltage, diameter, area, and inverse area data values. How could I calculate the resistance and resistivity with these numbers? I am pretty sure resistance is R=V/I and resistivity= RA/L , so I am not sure how I can calculate resistance without an I value.

Hello, I'm working on a project and I need some assistance. I need to adjust the negative supply voltage to an integrator opamp that I use for DC offset control based upon the resistance in a voltage divider elsewhere in the design. R12 is the trimmer resistor to adjust the CVS circuit and V5...

The microscopic Ohm's law is: J = sigma * E So the density in every point is proportional to the electric field in that point. My question. This sigma is also point-dependent? So the resistor could be made of different materials and ohm's law would hold for every point differently. Or is this...

Homework Statement This was an experiment we did in my lab. You're given a black box with four resistors inside, with resistances 20, 51, 100, and 200 ( k\Omega). The box has three plugs on it, labeled A, B, and C. You take your multimeter and plug into two jacks at a time and measure the...

Okay so here is my idea, not really sure how well (if at all) it would work but I am wondering if it would be possible (assuming battery technology is good enough) to ionise air in front of a formula 1 car (or plane or whatever) giving it a charge (like the way lightning works) , then creating...

Simple as that, I've uploaded the image. I don't really care about the exact value, I would prefer just to know the method. So how would I find the equivalent resistance between A and B? Note the component in the middle is a constant current source.

Wondering the best way to go about calculating the ability of a silicone wafer to withstand impact. Wanting to possibly use a small pc as a fracture barrier to indicate that a part was dropped and may potentially be damaged. Need it to handle 20G. Alternative mat'l suggestions would be...

Homework Statement Find the equivalent resistance between AB. Homework EquationsThe Attempt at a Solution I could not find any Wheatstone bridge or series parallel combination. Should I use star delta transformation ? If yes, how exactly should I use it ?

Homework Statement The resistance of a bobbinin 0 grades celcius is 3.35 ohm. What is its resistance in 50 grades celcius? thermal constant=0.0037 Homework Equations R1=R0[1+alpha(t-t0)] The Attempt at a Solution Using this formula R1=3.35[1+0.0037(50-0)]=3.35*1.185=3.96975, but the answer in...

Hi, I have been at this problem for days and I can't seem to see what I am doing wrong. Here is the circuit layout along with my work As you can see I am running into problem getting values of current that do not add up equal to zero. My professor has never discussed how adding a wire like...

Homework Statement When two same lamps are connected with the same battery. Their lighting will be greater when they are connected in series or parallel? Homework Equations Series U=U1+U2+U3+... I=I1=I2=I3... Parallel U=U1=U2=U3... I=I1+I2+I3+... The Attempt at a Solution The answer is when...

Homework Statement If the diameter of a wire (conductor) is dimidiated , then its resistance: A Remains unchangable B is diminiated C Becomes two times greater D Becomes 4 times greater Homework Equations R=constant*length/Surface The Attempt at a Solution Cross sectional area=pi r^2=pi...

Homework Statement The resistance of a wire (conductor) in cylindrical form is: A Disproportional with the length of the wire (conductor) B Disproportional with the square of the wire (conductor) section C Proportional with the square of the length of the wire (conductor) D Proportional with...

Homework Statement The carriage and its passengers start at rest at A. At B, the bottom of the ride, the maximum speed of the carriage is 20ms-1. The vertical distance between A and B is 110m. The length of the track between A and B is 510m. The mass of the carriage and the passengers is...

The formula to find the total resistance in a parallel circuit is 1/R=1/R1+1/R2+1/R3, but wouldn't it be easier to use R=1/(1/R1+1/R2+1/R3)? I've only ever seen the equation written like that once before, and I'm wondering if there's a reason as to why it's never really used?

Disclaimer: I'm not sure if this is the correct forum. An ideal conductor (ideal = no resistance) is essentially taking the electric field at one terminal and connecting it to the other terminal. Charge moves when it is in an electric field, electric field strength is in Volts per meter, or...

I was told that for resistors connected in series (whatever the equivalent resistance be) the current flowing through a circuit will be a constant Say i had 'n' number of resistors in series connected to say a battery such that the equivalent resistance was equal to that of an insulator, would i...

Homework Statement Q4) Calculate the thermal resistance of the heat sink required for the regulator of Q3 above given the information below [from the datasheet] and the data in the table. Q3 FIGURE 2 shows an adjustable voltage regulator using the LT1083*. The LT1083 develops a 1.25V reference...

Speaking just of long straight wires, not loops, coils or solenoids. Ideal wires have no resistance. Of course they would have no capacitance. And real wires have some very small amount of inductance, no? Firstly, would an ideal wire have some ideal nonzero inductance? Why/why not? After all...

Homework Statement When the resistor is R1, in the circle there is the intensity I1 and when the resistor is R2, the intensity becomes I2.Find emf and the inner resistance.[/B] Homework Equations I=emf/R+r The Attempt at a Solution I1=efm/R1+r I2=efm/R2+r efm is equal I1*(R1+r)=I2(R2+r)...

Homework Statement A battery is connected with a resistor R1=4 om and then it is replaced with the resistance 9 om. In both cases the heat released in the same time is the same. Find the inner resistor of the battery. Homework Equations Q=UIt (U-tension; I-intensity, t-time) I=e.m.f/R+r The...

The question in textbook:- A 4uF capacitor is charged by connecting it to 200V supply.It is then connected to an uncharged 2uF capacitor.How much electrostatic energy of the first capacitor is lost in form of heat and electromagnetic radiation? My question is that why the energy must be lost...

Homework Statement A 5V battery rated at 1800mAh has a soucre resistance of 10 Ohms. What is the maximum power that can be extracted from the battery? Homework EquationsThe Attempt at a Solution I understand that had the battery not had any source resistance then the power out would have been...

Homework Statement https://z-1-scontent-sin1-1.xx.fbcdn.net/hphotos-xtf1/v/t34.0-12/12435980_942112312550457_1708451532_n.jpg?oh=b29a5e9b2ff96bbf0e11932d081eb25e&oe=568A9B79 [/B] We need to find the equivalent resistance along A to B ie AB Homework Equations R=(1/R1 + 1/R2+...+1/Rn)^-1 ...

Hi. I am re-engineering a 40+ year old carburettor design. The current throttle slide has stress raiser flaws and is the same material as the mixing chamber that it slide interfaces with. The prototype slides were printed in ABS for fitment trials. The functional trials used Acetal allowing for...

Homework Statement : [/B] Given a voltage regulator with 6.8V Zener diode, input voltage range of 15-20V and load current range 5mA-20mA. Calculate the series resistance R for the regulator.Homework Equations : [/B] Applying KVL and no load situation, we get R = (V - Vz)/Iz where V is the...

Homework Statement A 2000 kg boat's motor can exert a force of 6000N. The water provides a resistive force of 2000N. What is the magnitude of the acceleration. Homework EquationsThe Attempt at a Solution that the boat has a 4000 N total force going foward

I'm trying to write a program to calculate the trajectory of a projectile with air resistance. I've made the following function which calculates the position of the particle based on a given launch angle and initial velocity: def traj_fr(angle, v0): #function that computes...

Hi guys. I'm looking into the modelling of a transmission line model (TLM) and feel that I'm understanding it fairly well. Although, one parameter keeps popping up with very little explanation as to what it actually is. It seems that to characterize contact resistance for a e.g. GaAs TLM with...

Homework Statement R = 10 Ohms Homework Equations Req = (1/R1 + 1/R2 + ... )(-1) Req = R1 + R2 + ... The Attempt at a Solution I honestly don't even know where to start... The obvious thing to do is 4R + 2R = 6R That's pretty much all I can come up with that makes sense... Any help?

Homework Statement http://imgur.com/uLZdBJC 27. The switch has been closed for about 1 h. It is then opened at the time defined as t 0 s. a. Determine the time required for the current iL to drop to 10 μA. b. Find the voltage VL at t 10μs c. Calculate VL at t 5tau. Homework Equations So I...

Hi guys. I'm looking into the modelling of a transmission line model (TLM) and feel that I'm understanding it fairly well. Although, one parameter keeps popping up with very little explanation as to what it actually is. It seems that to characterize contact resistance for a e.g. GaAs TLM with...