Consider 2 long and thin conducting wires of radius 'b' separated by distance 'a'. At one end, they are connected to a voltage 'V', and at the other end to an unknown resistance 'R'. Note that two parallel wires form a capacitor.
Neglect all resistance of the wires and the battery. Neglect gravity.
The long wires are at equilibrium. What is 'R'?
infinity
ReplyDeletebhaiya, infinity should be correct but, does some other resistance value also exist???
ReplyDeleteinfinity is a wrong answer.
ReplyDeleteI think resistance can be anything because loop is closed
ReplyDeleteBhaiya, is that the only data available? No mass or nothing?
ReplyDeleteI tried equating force between 2 wires due to field of one, on another(repelling force) with gravitational force, but I don't have the masses :|
Any special meaning of changing it to "equilibrium" from "stable" ?
ReplyDeleteCan they move with a constant velocity?
cmon...that would not change the answer...
ReplyDeletemagnetic repulsion is the only force i can think of, not getting how to get the equilibrium relation :(
ReplyDeleteexactly :|
ReplyDeletethough sambhav, bhaskar bhaiya ne kuch karaya tha class me AC k baad. not related to this, but you might get some hint :P
I can't remember it completely, but jahan tak mujhe yaad hai there were 2 current carrying wires lying at some distance or something....ummm..I forgot
Whatever it was, answer came that if velocity of wire was 1/root(Uoeo) (meu naught*epsilon naught) then it would be in eqbm, and that's the speed of light
haanji anant, main physics k question nhi bhoolta, us tarah se bhi sochkar dekh lia..:P
ReplyDeletewhat was that question? :D
ReplyDeleteanant, question you are talking about is in APP subjective. ki kitni velocty de do charged wires ko ki woh eqm mein rahey.
ReplyDeleteanswer-speed of light
And coming to this question, firstly obviously thought of infinity but, as bhaiya said it wrong, I think any resistance can be anything- as current is flowing in the loop so, repulsion but, the wires would be resisting that(as tension) so, eqm. And it is easy to resist as mutual force among wire contains nu(not)
two infinite vertical parallel rails with charge density 'lambda' at 'a' distance a from each other, both moving vertically at unknown speed, find this unknown speed for equilibrium
ReplyDeleteand btw, is anuj bhaiya k question main capacitance kahan se aa rhi hai? :O
hey, I got some hint- see the title. But, still didn't get it :)
ReplyDeleteis it R= (mu/pi)*c*log(a/b)...?
ReplyDeletewont be surprised if its wrong though.. :)
didn't exactly calculate the value of R. But got the relation i/q = c(a^0.5)/b where c = speed of light and i and q are values of current and charge on the plates during charging.
ReplyDeletethe capacitance in the problem is er.. the 'oliphaunt in the room'..
ReplyDeleteso i suppose i was wrong.. :-/
ReplyDeleteQ? plate? :/ Charging?
ReplyDeletewaise bhi kya tumhe lagta hai current carrying wire mein charges induce honge- they will only flow
ReplyDeletebhaiya, kal physics ka paper hai so, aaj soln post kar dena. thanx!
ReplyDeleteI was equating force of attraction exerted by one plate on the other plate to the magnetic force of repulsion between the two wires.
ReplyDeleteBut I am having a tough time eliminating the length of wire.
mere bhaaion kaunsi plate?
ReplyDeleteI meant the two wires. My bad :P
ReplyDeletei m sorry . wires and not plates :)
ReplyDeleteOk..here's the solution:
ReplyDeleteThe two parallel wires (just like 2 parallel plates) form a capacitor. Try to calculate the capacitance of the pair.
Now, when connected to a voltage source, the wires will develop charges/unit length. Hence some attraction.
Balance this with the magnetic repulsion.
please confirm capacitance is [pi*epsilon]/log(a/b)
ReplyDelete