Quantcast

Got Homework?

Connect with other students for help. It's a free community.

  • across
    MIT Grad Student
    Online now
  • laura*
    Helped 1,000 students
    Online now
  • Hero
    College Math Guru
    Online now

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

ganeshie8

Imagine a battery shorted with a very long conducting wire. Q : if the wire is uniform through out the loop, can i use V = E.dl directly (to know potential drop between two points) ? If yes, how can we extend the same concept to a loop containing few resistors in series ? I am stuck in Lec.9... pls help..

  • one year ago
  • one year ago

  • This Question is Closed
  1. quarkine
    Best Response
    You've already chosen the best response.
    Medals 2

    use the fact that I=constant for different R 's so E will vary with R directly for all R's(resistors)..

    • one year ago
  2. ganeshie8
    Best Response
    You've already chosen the best response.
    Medals 2

    not clear.. you mean loop length is constant ? and, equation V = E.dl doesnt say E varies with R... can you pls explain some more... ?

    • one year ago
  3. quarkine
    Best Response
    You've already chosen the best response.
    Medals 2

    i quote "Q : if the wire is uniform through out the loop, can i use V = E.dl directly (to know potential drop between two points) ?" ans : yes because the resistance is uniformly distributed. for discrete resistances in series the voltage is distributed between the resistances as the conducting wire has negligible resistance.. |dw:1339526221153:dw| since same current through both the resistors,therefore the V around each is in inverse ratio of the resistance values of the resistors.

    • one year ago
  4. nick67
    Best Response
    You've already chosen the best response.
    Medals 0

    If you have a uniform wire with circular section you can use the formula: \[R = \rho * L / S\] where R is the resistance in Ohm, p is the resistivity in Ohm*m, L is the wire length in meters, S is the wire section in meters^2. This way the total resistance in a uniform wire is directly proportional to its length.

    • one year ago
  5. ganeshie8
    Best Response
    You've already chosen the best response.
    Medals 2

    quarkine, for discrete resistances i have difficulty in understanding how voltage is distributed between the resistances only. you jumped directly to the resistance/voltage relation. still i dont see connection between V = E.dl & ohms law :( nick67 : i used lot of ohm's law & KCL/KVL in DC circuit analysis.. but i never developed good intuition of it. i understand collisions with atoms and energy losing stuff. but thinking of how potential difference develops across resistor is scary..

    • one year ago
  6. locnguyen
    Best Response
    You've already chosen the best response.
    Medals 0

    i think 2 part of your question are not related because resistance have nothing to do in the equation \[V = E \Delta l\] You can only derive Ohm's law with the help of this equation, and beside, the resulting Ohm's law is true for the wire, but cannot apply for resistors, since they normally have fixed values produced. the second part of the question is just simly Ohm's law.

    • one year ago
  7. quarkine
    Best Response
    You've already chosen the best response.
    Medals 2

    |dw:1339610745648:dw| here let R1>R2.. to move a charge from B to A you have to do more work than from C to B.. you cant use the formula V = E.dl as it is Wrong and is actually dV=E.dl and cant use dV=E.dl either because E=dV/dl is not a continuous (actually it is not differentiable) function around the loop as the value of E is different in loop's wires and in the resistor (which can be seen from the fact that a loop wire of length dl has different value of dV (almost 0) around its ends than the same length inside a resistor wire (much larger value))

    • one year ago
  8. ganeshie8
    Best Response
    You've already chosen the best response.
    Medals 2

    quarkine, this is the the best explanation :) now i understand fully why we cannot use dV = E.dl in series network... really appreciate the help thanks a lot!!

    • one year ago
  9. quarkine
    Best Response
    You've already chosen the best response.
    Medals 2

    glad to help :).it was a good question..

    • one year ago
    • Attachments:

See more questions >>>

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.