Resistance Definition and 1000 Threads

  1. B

    Calculate the multiplier resistance

    Question: My attempt: So the resistance of the multiplier resistance comes out to be 19.25 ohms?
  2. B

    What is the Correct Value of Multiplier Resistance?

    This is the problem itself shown below And this is what I have tried, I get an answer of 29 ohms Would you agree?
  3. E

    Putting internal resistance in series with a voltage source

    Suppose I have a galvanic cell, where I've arbitrarily set the (-) anode to have a potential of zero volts and the (+) cathode to ##\epsilon## V. The electrodes are connected via the load, but also via the solutions and salt bridge in the centre. Edit: The two trailing wires are connected to a...
  4. B

    Working out the shunt resistance for a galvanometer circuit

    Here is the problem I have tried to draw the set up for both cases which the question had described above, and came to these 2 equations. But I can't see how it would help me to work out the resistance of the shunt? Any help would be really great! Thanks
  5. V

    Regarding the work done against air resistance

    Here is the question: I have correctly calculated the power produced by the thrust force (P = Force x Velocity = 9.0 × 104W) , the work done by the thrust force over 3 minutes (W = Power x Time = 9.0 × 104 × 3.0 × 60 = 1.6 × 107 J) , and the gain in potential energy over this period (mgh =...
  6. B

    Finding the resistance of this shunt resistor

    How would I go about this question? Here is my attempt at it but I haven't really gone anywhere with this :oldconfused: Any help would be really appreciated!
  7. C

    Does the resistance of a material vary when introduced into water?

    Suppose we have a copper wire, of resistance R, and we introduce it in water, when applying now a certain potential difference between the two ends, will the intensity that circulates through the wire be the same, and therefore also the resistance ?, is there going to be a potential drop due to...
  8. K

    Discharging this capacitor in an RC bridge circuit

    The voltage source in the circuit below has been switched on for a long time when the switch S switches off. How long will it take before the current coming out of the capacitor has become less than 1 mA? My attempt: I am far from sure that my solution is correct. This is because i...
  9. A

    Engineering Problem with the Thevenin equivalent resistance

    Good day I have a problem to find the equivalent resistance from the capacitor point of view the solution says it's R1 but for me we still have R2 and R3 we have not deal with ! many thanks in advance
  10. Reneee

    What's the total amount of resistance in this kind of circuit?

    I am not sure how to treat the extra connections K12 and K34. My first guess would be (R1 and R2) are parallel and so are (R3 and R4) and (R5 and R6) ,so R_{total}= {R1*R2} /{R1+R2} +... Or maybe the behaviour is like this: (R1, R3, R5) are in series , and (R2 R4 R6) are, thus R_{total}=...
  11. M

    Engineering Find the output resistance in a amplifier (MOSFET) small-signal model

    I have to solve a problem related with an 'invented' (non-real) MOSFET working in its saturation region (amplifier). I have solved all the questions, but I'm unable to get the last one. Basically, I need to determine the output resistance of the amplifier as a function of other given 4...
  12. physics_CD

    Understanding Total Voltage in Parallel Circuits

    I really don't have any clue why the total voltage is equal to the voltage drop over the 3 Ω and 2 Ω resistors and independent of the 4 Ω resistor . Does it have to do with parallel circuits?
  13. bagasme

    Wheatstone Bridge: Substitution Resistance Formula Derivation?

    Hello, In high school, I had been taught about finding substitution resistance from Wheatstone bridge. The formula: a. If the cross product of ##R1## and ##R3## is same as ##R2## and ##R4##, the galvanometer in the middle (##R_5##) can be omitted and use series-parallel principle to solve for...
  14. J

    Engineering DC bias current and small-signal resistance

    We are given that ##i_D = 8\cdot 10^{-12} (e^{v_D/20m} - 1)## Hence ##i_D' = e^{50 v_D}/2500000000## and ##i_D'' = e^{50 v_D}/50000000## Then I have that ##\delta i_D \approx\frac{ e^{50 v_D}}{2500000000} \cdot \delta v_D = \delta v_D / 5## Cancelling ##\delta v_D## from boh sides and solving...
  15. J

    Engineering A circuit with non-linear devices

    I honestly don't know how to quite even begin this problem. Looking at Fig 3-2, the slopes of the graphs are 1/R, and hence where the slopes are 0, we have infinite resistance, in which case current wouldn't flow through that resistor and hence simplify the circuit. So I was trying to find...
  16. J

    Engineering Finding voltages in a linear circuit

    From the circuit I have: ##-v_b + v_a + V = 0## ##v_b - V = v_a## ##i_1 = (v_b - V)/R_1## ##I + i_2 = i_1## ##(v_b - V)/R_1 = I + v_b/R_2## From this last equation I get ##v_b = 10.8## and hence ##v_a = 5.8##. However, apparently that is wrong. (And hence my answers to #2 were all wrong as...
  17. J

    Engineering Solving Circuit Equations: A Struggle

    I am having a hard time solving this. Letting \$i\$ be the current flowing into ##R_3##, ##i_1## the current flowing through ##R_1## and ##i_2## the current through ##R_1##—and the node between R3 and R1 be e_1; Using KVL and KCL, I've managed to find that ##i + I = i_1 + i_2## Hence...
  18. cookiemnstr510510

    Deciphering this problem statement: Air resistance on projectiles

    I am struggling with our equation and where to plug in my velocities and forces? After looking at my book I don't understand why p(t) would be where I plug in force, and why variable "t" is where we plug our velocity in? When the problem says "what happens if you try to use a polynomial of...
  19. penroseandpaper

    Platinum resistance thermometer and Kirchoff's Laws

    Hi, I found this question/s online and I was wondering if somebody was able to explain the answer given, specifically the first bit that says R1/(R1+R2) = R4/(R3+R4) (is this something to do with an equivalent resistor to replace the two in series on each side? But why are R1 and R4 the...
  20. ramadhankd

    Can We Design a Tube to Resist Fluid Flow?

    Hello everyone, I want to ask something. Can we design a tube that can completely resist the flow of a fluid? Maybe using either viscosity or surface tension approach? Thanks
  21. J

    A Current spreading decreases resistance?

    I have a Question to the Independence of the probe distance for a four-probe-measurement technique. In a paper the author is argument that the resistance of a 2D shape is NOT dependent of the distance between the probe which measure the voltage drop, cause he says that the current spreading...
  22. louisnach

    Obtaining the series and shunt resistance of a photodiode from the datasheet

    Hello, Hello, For a project , i need to modele a photodiode with a current source in paralelle with a shunt resistance and in serie with a resistance to use it in a bigger circuit. The photodiode we will use is SFH7050, the datashhet is provideed here...
  23. C

    Does Polarity and Current Direction Affect Energy Flow in AC Circuits?

    I assume that because there is a resistance, the polarity of the voltage must be the same as the charge flow, and thus the current, in order for energy to flow in the same direction. For instance, could I use the example of a light bulb (the resistor) plugged into AC lines; we know that if the...
  24. M

    Modeling a ball thrown vertically including drag from air resistance

    So I'm trying to figure out how to model a ball getting thrown vertically with the starting velocity v_0. So I've come up with a differential equation which I'm pretty sure is correct: Where D is a constant. So far so good. My problem is solving this. This is my attempt: And when i do this...
  25. E

    Electric current and resistance question

    Homework Statement:: problem solving You build a wire by combining an 8 inches copper wire with a 10 inches nichrome wire. If their combine resistance is 10 kΩ, find the cross section area of both wires. The nichrome wire has twice the area of the copper wire. Homework Equations:: I = V/R...
  26. E

    Electric current and resistace problem

    This is a problem I have been strugglying since I don't know if I should work it together or apart I ask my teacher and I don't know if I listened well but he told me to use the combine resistance and substract it with the restistance of the material. You build a wire by combining an 8 inches...
  27. J

    Introductory Circuit Analysis—power ratings

    I am going through "Circuit Analysis for Dummies". On pg 18, it says, "If you calculate the power dissipated as 0.1 watts, then a 0.25-watt resistor can handle this amount of power. A 0.125-watt resistor should be able to handle that amount as well, but when it comes to power ratings, err on the...
  28. L

    Determine the effective current value in the circuit with C and R

    Given: U = 220 V f = 50 Hz r = 20 Ohm C = 100 μF Find: I Solution: 1) Xc = 1/(ω*C) = 1/(2*π*f*C) = 1/(2*π*50*10^-4) = 31.83 Ohm 2) R_eq - equivalent resistance R_eq = (r*Xc)/(r+Xc) = (20*31.83)/(20+31.83) = 12.28 Ohm 3) I = U/R_eq = 220/12.28 = 17.9 A True answer given in the textbook is 13 A...
  29. K

    "Heat resistance temperature" and melting point?

    I've got a kitchen bowl made of polypropylene, it states that the "heat resistance temperature is 90 degree cel", while on Google, I found that the melting point of PP is 160 degree cel. I understand that melting point is the temperature in which the atoms/molecules change its state from solid...
  30. hjannett

    Corrosion resistance of 6105-T5 anodized aluminum for wastewater?

    Hello, I'm looking for structural materials that will act as the frame (skeleton) for the housing surrounding a waste container. The frame will structurally support HDPE panels as walls. This will be above ground for use in Uganda (but we can ship materials), under a raised squat toilet hole...
  31. M

    Find the time when the projectile runs into the hill (with air resistance)

    vy=vter + (vy0 -vter) e-th/τ where tau=m/b EQ 1 Okay, for part a, I used Eq 1 I let vy=vy(th)=0 --->The reasoning is that the projectile would stop moving for a short time when it hits the incline, but I have a feeling that reasoning is faulty I let vy0=v0sinθ Then the equation became...
  32. M

    Engineering I can't determine the capacitive and inductive resistance of the circuit

    Hi, I'm trying to solve this but it becomes difficult. I'm using KCL and I repalce ZL = j0,1ω (Ω) , ZC=... etc. Finding 3 equations with 3 unknown variables (plus the ω). And now is the time for Cramer's rule. I'm not sure if I should move on. What do you say ? I'm on track ? Thanks. ..
  33. L

    How to find the equivalent resistance of this electric circuit?

    Summary: How to find equivalent resistance of the electric circuit? I need to solve the following problem: Calculate equivalent resistance of the circuit (figure1), if all six resistances are the same: r1 = r2 = r3 = r4 = r5 = r6 = 100 Ohm. True answer: 66.6 Ohm. I tried to solve this...
  34. D

    Parallel circuit with internal resistance

    4 resistors R1= 10 Ohm R2= 7 Ohm R3= 6 Ohm R4 = 18 Ohm, internal resistance of source is 0,5 Ohm and supply voltage is 27V Total resistance in parallel resistors 1/R = 0.465 taking the inverse of that i get 2,15 Ohm. Add to that the internal 0,5 and the total comes out to 2,65 Ohm. Total...
  35. Physics lover

    Maximum power in this resistor circuit

    My attempt-: So the resistance is coming to be negative.Can anyone tell me my mistake.Thanks.
  36. Another

    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?
  37. H

    Green's function and the resistance across a Hypercube

    Homework Statement: I do know how to solve the resistance network problem in two dimensions. However, in this problem they want it in 3 dimensions and higher and I don't know how to do that Homework Equations: - In the picture you can see the solution to the two dimensional version
  38. J

    Wear Resistance: AISI 1074/75 VERSUS 304 2B Annealed Stainless

    Can anyone here tell me which of these two materials would have a greater resistance to wear? I understand that higher carbon content generates greater hardness, which provides relatively higher wear resistance. And alloying can increase wear resistance -- but I'm not sure how to directly...
  39. D

    Resistance and Precession Torque of a Gyroscope

    Hi, Say there's a gyroscope with moments of inertia Ix, Iy and Iz spinning around a vertical z-axis (see attached illustration) with a given angular velocity ωz. Notice that the gyroscope is floating in space as in that there's no gravity acting on the gyroscope. Now I apply a torque τx...
  40. TachyonLord

    Resistance of Platinum decreases with an increase in temperature ?

    Basic Procedure The experiment basically involves finding the null point on the Carey Foster's bridge with the PRT as the unknown resistance and using a Resistance box as the variable resistance. In the above diagram, P and Q are 2 fixed resistors of equal resistances. For obtaining the first...
  41. A

    Determining Resistance of a Copper Wire Without Knowing Its Resistivity

    What i did is: ##R=\rho\frac{l}{\Sigma}=\rho\frac{l}{d_2^2\pi-d_1^2\pi}## The problem is that I don't have ##\rho##. Is there a way to find ##R## without knowing it? Many thanks.
  42. A

    Thermal Resistance of a Hollow Circular Cone

    We can write our radius as a function of the height, z, of our cone: $$R(z) = \frac{R_2 - R_1}{h} z + R_1$$ Where h is the height of our cone, ##h = \frac{L}{40}##. Our cross sectional area, $$A = 2 \pi R t$$ can then be written as $$A = 2 \pi t [\frac{R_2 - R_1}{h} z + R_1]$$ This I am all...
  43. M

    Zero Friction on the Moon: Driving at Constant Velocity Without Air Resistance

    Suppose we are driving on moon (I mean there is not air resistance) at a constant velocity. Suddenly the car goes on an icy land (the friction is zero). What happens? In other words, if we drive at constant velocity and there isn't air resistance, Is there any friction force between tires and...
  44. D

    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...
  45. A

    How can I calculate the equivalent resistance of this circuit?

    i was trying to calculate equivalent resistance of this circuit and that was my attempt : 1) i can see two parallel 20 ohm resistors so equivalent resistance = $${20 \over 2} = 10 ohm$$ 2) now we are left with 20 ohm resistor and 10 ohm resistor which are connected in series so equivalent...
  46. A

    Trying to get equivalent resistance of a circuit

    i had a problem in my textbook asking me to get equivalent resistance of a circuit , i ended up getting 23.7 ohm as my answer but my textbook says that the correct answer is 100 ohm you can see my attempt here : imgur link : i really want to know what went wrong with my steps thanks in advance
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