http://www.ck12.org Chapter 19. Electrical Circuits
The current through each resistor can be found using the voltage drop and the resistance of that resistor:
I 1 =
VT
R 1
=
90 .V
60 .Ω
= 1. 5 A I 2 =
VT
R 2
=
90 .V
30 .Ω
= 3. 0 A I 3 =
VT
R 3
=
90 .V
30 .Ω
= 3. 0 A
The total current through the circuit would be the sum of the three currents in the individual resistors.
IT=I 1 +I 2 =I 3 = 1. 5 A+ 3. 0 A+ 3. 0 A= 7. 5 A
The equivalent resistance for this circuit is found using the equation above.
1
RT
=
1
R 1
+
1
R 2
+
1
R 3
=
1
60 .Ω
+
1
30 .Ω
+
1
30 .Ω
=
1
60 .Ω
+
2
60 .Ω
+
2
60 .Ω
=
5
60 .Ω
RT=^60. 5 Ω= 12 Ω
The equivalent resistance for the circuit could also be found by using the total voltage drop and the total current.
RT=VITT=^907. 5 .ΩA= 12 Ω
Summary
- Parallel electrical circuits have multiple paths the current may take.
- VT=V 1 =V 2 =V 3.
- IT=I 1 +I 2 +I 3.
- R^1 T =R^11 =R^12 +R^13.
Practice
Questions
http://www.youtube.com/watch?v=apHkG4T6QHM
MEDIA
Click image to the left for use the URL below.
URL: http://www.ck12.org/flx/render/embeddedobject/63607Follow up questions: