a generalised situation

I would like to have everybody's idea about the following problem:

suppose we keep two circuits with one loop each(radii x,y) side by side.(resistance r1,r2,, emf e1,e2). not neglecting mutual and self inductance, give a qualitative and quantitative idea about current at any moment through the circuits.

6 Answers

1
Rohan Ghosh ·

wait posting the solution

1
Rohan Ghosh ·

let us assume x<y

then for loop one by applying kirchoffs law

μ0πx/2(di1/dt)+μ0πx2/(2y)di2/dt + e1 -i1r1=0

for loop 2

(μ0πx/2)di1/dt+(μ0πy/2)di2/dt + e2 -i2r2=0

solving these i am getting an equation of the form

A(d2i1/dt2)+B(di1/dt)+Ci1+D=0

9
Celestine preetham ·

Qualitative :

as nothing is mentioned in Q , i suppose both emfs are clockwise
Now inc in i1 will induce backemf in ring one and forward emf for ring2
similar case for i2

Quantitative:

L1 ,L2 - self inductance
K1,K2 - mutual inductance ( i hope u arent asking derivation of exact formula , its tedious )

then for loop one by applying kirchoffs law

L1(di1/dt) - K2(di2/dt) + e1 -i1r1=0

for loop 2

L2(di2/dt) - K1(di1/dt) + e2 -i2r2=0

solving these i got something very interesting!!
--------------------------------------------------------------------------------------------------
(L2L1 - K2K1)d2i1/dt - (L2r1 + L1r2 )di1/dt + i1(r1r2) = e1r2
-------------------------------------------------------------------------------------------------

now the abv eq is solvable and has multiple solutions .

but one interesting solution that can be found by observing is i1 = e1/r1 (which is a constant and the other derivatives are 0 )

but nature doesnt permit that solution as for i to be established , it takes a small but definite time ( as speed of EM waves = c )
but after infinite time , i1 = e1/r1 obviously and similar for i2 .
can u solve the abv eq using mathematica and post it ith power ??

1
voldy ·

this one's similar to a transformer. na ?

1
voldy ·

one more Q . r1 r2 are net resistances offered by the entire ckt or reistacnes or coil and source is to be tkaen separately ????

9
Celestine preetham ·

r1 r2 entire ckt resistance

and can someone solve the DE ?????

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