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Given is the following circuit. What is the current I?
http://i.imgur.com/irjolvW.png
I can't figure out no matter what I try. No one gives a direct answer. I'm trying to study for a quiz. This is really stressing me out. Please help. I've tried applying KVL. Apparently I'm doing it wrong but no one tells me what I should do differently. **** me.
6 Answers
- Mr. Un-couthLv 77 years agoFavorite Answer
We cant tell you what to do differently without seeing your attempt. However, since
it's rather obvious that you are suffering from a severe case of the "Red A$s" ; here's how you do it..
.
I = V/R = 10V/ (2 + [(12)*(4)]/(12 + 4) }Ohms = 10V/5 Ohms = 2 Amps
- Randy PLv 77 years ago
Since I is the total current in the circuit, V = I * R where R is the equivalent resistance of the circuit.
The 12 ohm and 4 ohm resistors are in parallel, so use 1/R = 1/12 + 1/4 to find out the equivalent of that part. Then add 2 ohm, which is in series. That gives you your total R for the circuit. Plug it into V = I * R.
- TechnobuffLv 77 years ago
(12 x 4) /(12 + 4) + 2 = equivalent resistance of 5 ohms.
I = (E/R) = 10/5, = 2A.
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- Ray;mondLv 77 years ago
Both answers are correct = the equivalent resistance is 3 ohms + 2 ohms = 5 ohms
- oldschoolLv 77 years ago
We have to determine what resistance the voltage source "sees"..
First the 2Ω and then the parallel combination of 12Ω and 4Ω = 12*4/(12+4) =48/16 = 3Ω
Thus the source sees 2+3 = 5Ω
Therefore I = 10V/5Ω = 2A
When the 2A enters the junction of the 12Ω and the 4Ω a current divider shows that: 2A*4Ω/(12Ω+4Ω) = 0.5A into the 12Ω
and 2A*12Ω/(12Ω+4Ω) = 1.5A flows into the 4Ω
Notice that 0.5A+1.5A = 2A and 0.5A*12Ω= 6V and 1.5A*4Ω = 6V
Notice that 10V - 2A*2Ω = 10-4 = 6V which is the voltage at the junction of the 12Ω and the 4Ω