Read about resistance | 200 Discussions | Page 1

  1. 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.
  2. F

    What is opposing resistance?

    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.
  3. Kaushik

    B 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...
  4. R

    Where r came from?

    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.
  5. 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.
  6. 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...
  7. 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...
  8. 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}=...
  9. physics_CD

    What is the total voltage?

    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?
  10. 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...
  11. 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...
  12. J

    Engineering Finding the Thevenin equivalent Resistance for circuit with voltage dependent sources

    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...
  13. C

    Electrical current question

    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...
  14. 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...
  15. 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...
  16. 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...
  17. 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.
  18. Another

    I 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?
  19. 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...
  20. P

    How to estimate a constant drag coefficient of a boat?

    Hi there, I have modelled with MAXSURF a few variations of a prehistoric logboat in order to test a few theories. Now, I am trying to look at resistance-performance over a range of speed. To do so, I need to include a constant drag coefficient without knowing the drag force and velocity (both...
  21. Dr-LucienSanchez

    Calculate the total resistance by integration using the conductivity equation

    (i) Dividing the rod into thicknesses of dx we get discs of area A with lengths=dx so using (****) we have the resistance of a typical disc (between point x' and x'+dx) as: (1) ##R(x'dx)=\frac{dx}{g(x)A}## (ii) Using (1) and (*) and the integrating from a to b of the entire rod we get...
  22. DaynaClarke

    Resistors in Parallel or Series?

    Given that they're all on the same branch, I had assumed that they were in series with one another. But with the middle resistor having being on the middle of three branches, it looks parallel. Like I said, I have a feeling it's in series (making the answer 3R). This question is from a past...
  23. F

    Engineering Help me finding the current in here please (Circuit analysis)

    Hi! I've been struggling with this. Original exercise here: Find the value of Iy when R=0. And the value of Vx when R is infinite. For the first part of the question I did this since R=0: I've tried to solve this circuit and I get that Iy and I5 are 0 A, and this can't be possible since Iy...
  24. Adesh

    I How to solve a complex equation to get the current?

    I was reading The Feynman Lectures on physics http://www.feynmanlectures.caltech.edu/I_23.html chapter 23, section 4. In it he derives the equation for current when inductor, resistor and capacitor is connected in series with an alternating voltage source, he derives this equation:-...
  25. K

    B How a Secondary Resistor affects the Transformer Primary Side?

    Let's assume a 2:1 transformer which has a 100V Source connected on the primary circuit and has no/negligible resistance, on the secondary circuit a 5 Ohms resistor is connected. Using the 'Impedance Transfer/Reflection' method, the primary circuit would act as if there was a 25 Ohms resistor...
  26. V

    A few questions concerning voltage, current and resistance

    [ mentor note: post adjusted to conform to hw template and some spellings fixed ] 1. The Problem I have some few questions that connect voltage, current and resistance. Imagine that we have a circuit that consists of a battery (5V), 2 resistors. Now once we close the circuit, battery would do...
  27. bornofflame

    RC Circuit - Rate energy is dissipated in the resistor

    Homework Statement 1. A 2.01 uFcapacitor that is initially uncharged is connected in series with a 6.51 kΩ resistor and an emf source with 74.6 V and negligible internal resistance. The circuit is completed at t = 0. a) Just after the circuit is completed, what is the rate at which electrical...
  28. B

    I Effective Resistance (Fluid Mechanics)

    Imagine you have a vertical pressure head 2m tall with water flowing down to height 0m and emptying. Through this length we have 3 identical tubes of resistance R and length L. Assuming I know the volumetric flow rate(Q) as a function of height, how can I calculate the resistance of each tube...
  29. Celso

    I Power waste (conceptual doubt)

    I'm currently in a undergrad level course of eletromagnetism and my professor found it useful to remember quickly of some relationships that we see in high scool, among them power waste. I got the formulas, since they're simple and are direct derivated from the definitions of electric current...
  30. G

    Explaining a signal converting circuit

    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...
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