Resistance Definition and 1000 Threads

  1. P

    Why Can't Current Flow Between Two Same Voltage Nodes?

    The question is to find the resistance between points A and F. I understand that the resistor between OC can be removed. From this point onwards, resistor OC has been removed. Let the far right point of the diagram, where i5 and i7 exit from, be B. Is it possible to detach the remaining...
  2. I

    Calculate Input Resistance: Formula & Tips

    I want to calculate the input resistance ,but i don't really know how to do it .am not sure is the formula R1(1+BA0)?
  3. Tim86

    DC current through a resistor circuit

    Summary:: Current through a certain resistor in a mixed dc circuit. Hi, Sorry if this is the wrong forum. I'm trying to work out the current through R1.The answer I need is 2 Amp, which I have confirmed with a simulation software. I have calculated the source current as 8A, the current past...
  4. F

    Tension in rope for non-uniform circular motion with air resistance

    I'm trying to solve this problem using an rtz coordinate system, and Newtons second law. I know that mar = (m(v)2)/r. I'm failing to understand how mg and the drag force affects the solution and how I would set it up. I know if it was at the bottom of the circle that mg would be added to the...
  5. J

    Automotive Rolling resistance coefficient on sand

    Hello I,d like to find or to calculate Rolling resistance coefficient on sand tyre 37/12.5 R37. Thanks for your help
  6. hquang001

    Finding I3: Resistance Ratio Calculation

    Should it be I3 = \frac{(R2+R4)}{(R2+R4) +R3} I or I3 = \frac{R2}{R2 +R3} I
  7. willDavidson

    Capacitor Insulation Resistance

    Hi, I am trying to find the insulation resistance of a specific capacitor. I've posted on balancing resistors before and got some pretty helpful information. The previous datasheet gave the information in a different manner though. I'm hoping someone can help me decipher the insulation...
  8. D

    Calculating the resistance in a compensating circuit for a thermocouple

    Homework Statement:: A K-type thermocouple is connected as shown to sense temperature. The temperature zone is at 25°C. The RTD has a resistance of 100 at 0°C and a TCR coefficient of 0.00385. A 5V power supply drives the circuit. Calculate R2 for proper compensation. What is the emf produced...
  9. jedishrfu

    COVID Resistance from Neanderthal DNA

    https://www.cnn.com/2021/02/16/health/neanderthal-gene-coronavirus-scn-wellness/
  10. Andrei0408

    Calculate the equivalent resistance

    R1 = 2 ohms ; R2 = 2 ohms; R3 = 1ohm First figure: I need to calculate the resistance between: a) A and C and b) A and B a) R1 and R3 are in series => R13 = R1 + R3 = 3 ohms R13 and R2 are in parallel => 1/Rp = 1/R13 + 1/R2 => Rp = 1.2 ohms b) Here, between A and B there is only R1 so the...
  11. H

    Resistance calculation -- Comparing coax cable insulator resistances

    Since both cylinders have the same material, this implies the density is the same. Length is also the same based on the question. We only need to compare the radii for resistance. R2 = pi ((2b)^2 - (2a)^2) R1 = pi (b^2 - a^2) R2/R1 = 4, so my answer is C. But, the given answer is A. Where did I...
  12. brotherbobby

    Vertical flight with air resistance

    I suppose the trick in this question is to realize that the drag acts in opposite directions when the ball ascends and descends and that the ball actually takes less time to rise and more time to fall than normally. I make a small sketch of the problem alongside. Attempt : The total time of...
  13. theycallmevirgo

    How Is Thevenin Resistance Calculated in R1 Parallel to R2 Configuration?

    The attached image (Horowitz & Hill Student Manual for 2nd ed) gives thevenin resistance and voltage for the network R_1+(R_2||R_L) as R_th=R_1||R_2 E_th=E_in(R1/(R_1+R_2)) E_th is self-evident (voltage divider) but how in the world they get R_th i beyond me. If there is no load, isn't R_1 in...
  14. N

    What is the impedance of the human body and why does it vary?

    I was researching what the total electrical resistance of the human body was and got some quite far ranging values. It seems to range from 1, OOO to 1OO,OOO ohms. Some quite elaborate ways of testing it too. Then I thought I'd just get the old multimeter out. I have two and both measured about...
  15. T

    PM Generator and battery resistance

    I have a burned stator for a PM generator mounted in the accessory case of an internal combustion engine. The stator has 2 sets of 5 coils creating 2 20 amp generators. I am using a lithium battery and the engine builder blames the battery for the burned stator. He says the lithium battery...
  16. P

    The resistance of an element shaped like a half-cylinder

    So I started doing this with formula: S is equal to π/2*(r2^2-r1^2) l is equal to h Is it correct ?
  17. T

    Calculating air resistance for a cart rolling down a ramp

    I am doing a physics lab where we are supposed to calculate air resistance and find the impacts of velocity and cross sectional area on air resistance. For the experiment, we rolled a cart down a ramp and measured data using Pasco Capstone software. When rolling the cart down the ramp, we...
  18. LCSphysicist

    Electrodynamics problem -- Calculating the resistance of ocean water

    A return path for the current was provided by the ocean itself. Given that the resistivity of seawater is about 0.25 ohm-meter, see if you can show that the resistance of the ocean return would have been much smaller than that of the cable. (Assume that the electrodes immersed in the water were...
  19. A

    Electric Circuit: Path of Least Resistance

    I figured that when you close the switch the current from the upper cell will travel through the closed switch due to it being the path of least resistance, essentially the resistor between cells is unused (was my first thought). I'm not entirely sure how to progress with this question.
  20. J

    Is capacitance more fundamental than resistance?

    When we have electrical resistance it is based on dissipation of energy, when we have reactance it is a consequence of charge accumulation in capacitance. Together they form impedance. But let's consider what exactly is responsible for dissipation in case of resistance? Is not it because of...
  21. penroseandpaper

    Quadratic air resistance clarification

    Hi all, I've been trying to follow a question I came across on a website. And I'm able to understand everything up until the separation of variables for solving the differential equation and coming to a solution with arctan. But there are a few things that aren't explained that I was hoping...
  22. E

    How to calculate the resistance of a series circuit?

    Why we say that the resistance of the series curcuit is equal to the sum of the resistances of the resistors?
  23. greg_rack

    Percentage increase in resistance to motion

    So, I simply used the percentage increase formula for the resistance force, but what I come up with is a 9.5% increase, as opposed to the 44% it should be... Here's my procedure:
  24. H

    Solve this integral involving a quadratic and linear air resistance equation

    Hi, I'm trying to solve this integral and then isolate V, but I can't get the right answer. I don't know where is my errors. I probably muffed the integral. ##-bv -cv² = m\frac {dv}{dt}## ## \int_0^t dt = - m \int_{Vo}^v \frac {dv}{bv+cv^2} ## I get this after the integration ##t =...
  25. B

    Finding the potential difference of a diode

    I've tried doing it but i haven't been able to find the resistance of the diode.
  26. A

    Equivalent resistance of a section of a graphite ring

    I considered that the lengths of pi/4 and 3pi/4 would be in parallel: 1/R = 1/30 + 1/10 R = 7,5 ohm But the answer is 30 ohm. Where am I missing and how do I calculate the potential of the voltmeter.
  27. haushofer

    Rolling resistance when speed is zero

    Dear all, I have a very simple question. The rolling resistance (rr) of, say, a car, is defined as being proportional to the normal force/weight of an object. That seems reasonable: ##F_{rr} = C_{rr} \times F_N## The coefficient C_{rr} is a constant, depending on the materials. But now a...
  28. aspodkfpo

    What is the relationship between torque, linear force, and rolling resistance?

    Say that I have a round object on a table and it is still. If I apply a force and it doesn't move the resistive force is rolling resistance rather than a frictional force right? Now I must be able to apply forces in different amounts until it exceeds a boundary for the object to move similar to...
  29. Samama Fahim

    Calculating the Thevenin's Resistance of a Breadboarded Circuit

    How would we calculate the Thevenin's resistance for the above circuit? The right answer for this circuit is 1.5 kOhm. $$R_{567} = R_7 + (R_5 \parallel R_6) = .5 + .67 = 1.2 k\Omega$$ $$R_{34567} = R_3 + (R_4 \parallel R_{567}) = 1 + .75 = 1.75 k\Omega$$ $$R_{TH} = R_1 + (R_2 \parallel...
  30. jisbon

    Simplifying Complex Circuits: Using Delta to Y Transformation

    Not sure what I can do to proceed on here: Should I be using the Delta to Y transformation? Wouldn't be able to simplify using simple series and parallel circuits, and hence am looking for any clues I might need to solve this problem. PS: ForDelta to Y transformation, it seems that the 10 and 8...
  31. F

    What Is the Opposing Resistance for a 14ohm and 10ohm Circuit?

    I don't know about it. Please help. It wasn't letting me to post until I typed something here. So I am typing this.
  32. Kaushik

    Does potential drop when a charge flows through a wire w/ 0 resistance?

    Let us connect a battery of potential difference V to a wire. There is no resistance. Nothing! Now the battery creates some potential difference and the charges in the conducting wire move due to the Electric field created in the conductor by the battery. So, as the charge moves, its potential...
  33. e2m2a

    Does Rolling Resistance Change with Speed on Polyurethane Wheels?

    I have conducted an experiment which involves measurements of the velocities of a carriage moving in a straight line which has 4 polyurethane caster wheels attached to it. (The kind you can get a hardware store.) In one phase of the test the carriage is pushed at about .1 meters per second. In...
  34. P

    How is force applied? Is resistance or load necessary for force to exist?

    I don't know if this is a dumb question, but I just can't seem to wrap my head around it. I can imagine and feel when I'm pressing against a wall, that there's a force. Especially when the wall is not moving, I can continually increase the strength of my push and feel a greater resistance from...
  35. M

    Equation for the Internal Resistance of a Battery

    Hello, i am currently working on a project where i have to calculate the internal resistance of a battery based on the voltage drop caused by placing a resistor over the battery. I am an EE, and i understand how i can calculate the IR by schematic, but i found this equation: ((Open circuit...
  36. lucas pentland

    Net forces on a boat (propulsion, water and air resistance)

    2500 N [south] + 3200 N [south] = 5700 N [south] 5700 N [south] - 6000 N [north] = 300[north]
  37. S

    Calculating Total Resistance in a Circuit: Delta - Y Formula or Simpler Method?

    To find total resistance between 22 Ω, 14 Ω and 4.5 Ω should I use delta - Y formula? Or there is other simpler way? Thanks
  38. R

    Uncovering the Origins of the Symbol 'r' in Mathematics

    Summary:: I have a question that I don't understand but you may know where r was come from. I mentioned about my question on the addition.
  39. zoyash

    Electric Current and Resistance

    I have attached my solution to this problem but I think I got the wrong answer.
  40. S

    Finding Equivalent Resistance Using Symmetry and Kirchhoff's Laws

    By the use of symmetry, I have found that equal currents will flow through opposite edges like A-C and C'A', but still, the use of kirchhoffs current and voltage laws lead to four equations in four variables which I am not able to solve, neither I am sure that the four equations which I have...
  41. jaumzaum

    Resistance Association - How to solve this exercise in the proper way?

    This was an exercise from the 2011 admission test of an university from Brazil: 40 identical generators with electromotive force 1,5V and resistance 0,25 Ohms and one resistor with resistance 2,5 Ohm are associated in such a way that the 2.5- resistor dissipates the greatest energy per second...
  42. R

    Please check my calculation of the resistance of this wire shape

    I explained what I want to tell you in the picture I add. Thanks in advance.
  43. V

    How to calculate the equivalent resistance in this Circuit?

    I start from far right: Green and blue are parallel Connection: This in turn is in series connection with black resistor: and so on ... This is what I'm ending up with My final equivalent resistance is (275/17) Ω. Is this correct?
  44. K

    Calculate the current in all parts of this electric circuit

    In the circuit below, the output is 23 W across the resistor with the resistance 6 Ohm. Calculate the amount of current in all parts of the circuit as well as the polarity and EMF ε of the unknown battery. Circuit: My attempt: I get 6 unknowns with 5 equations. I don't know how to find the...
  45. CraterHater

    Help with adding air resistance into my projectile trajectory function

    Hey, I am working on a video game in which there will be archers who have the ability to shoot at enemies. My game is two dimensional and I am trying to calculate the angle at which the archer, given an initial velocity, has to shoot in order to hit the target perfectly. I came up with the...
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