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posted by  Valp on 5/19/2008 2:03:09 PM  |  status: Closed  

help me please, will rate

Course Textbook Chapter Problem
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Question Details:
Find the current in the 10.0 resistor in the drawing (V1 = 25.0 V and R1 = 24.0 ).
wrong check mark A
Specify the direction of the current.



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Guru
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posted by ahtinus on 5/19/2008 2:32:00 PM  |  status: Live
Asker's Rating: Somewhat Helpful   
Valp's comment:
"not quite, thanks though"
Response Details:
 
 
 There is a single node and assume node voltage be V
and as per KCL,,the sum of currents is zero
 
so
 
V - 10/ 24 + V -10/10 + V + 25 /5 = 0
 
V = 18.78V
The current in 10Ω resistor = V-10 / 10 = 8.78/10 = 0.878A from top to bottom
 
 
 
 
Sage
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posted by D.J84 on 5/19/2008 2:54:14 PM  |  status: Live
Asker's Rating: Somewhat Helpful   
Valp's comment:
"not quite, thanks so much tho"
Response Details:
LET voltage at A =0
i1=(10-VB)/24
10-24.i1=VB-----------1
i2=(10-VB)/10
10-10.i2=VB-----------2
from equation 1 and 2
i1=(5.i2)/12
VB=(i1+i2).5+25-------3
from equation 2 and 3
10-10.i2=(i1+i2).5+25
-3.i2=(5.i2)/12+3
-[(41.i2)/12]=3
-i2=36/41
-i2=0.8780
i2 is comming out to be negative
∴the direction of current is from B to A ie from top to bottom
Guru
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posted by Pradeep on 5/19/2008 2:56:10 PM  |  status: Live
Asker's Rating: Helpful   
Valp's comment:
"it wasn't negative, but thanks alot for the explanation"
Response Details:
Pupil
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posted by Army Engineer on 5/19/2008 3:23:54 PM  |  status: Live
Asker's Rating: Lifesaver   
Valp's comment:
"thanks so much for the explanation"
Response Details:
soΩ
 
7.05Ω + 5Ω = 12.05Ω
 
the two 10V DC sources are in parrallel and both are in series with the 25V source.
 
So total Voltage is 35 volts.  total current.
Voltage drop across the 5Ω resistor =
this leaves 20.5V for the parrallel branches.  Voltage drop across parrallel branches is equal.
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