1. Current Directions and
Voltage Polarities

2. Current Directions and
Voltage Polarities

3. Current Directions and
Voltage Polarities
Electrical Systems I
Voltages are assigned polarities that indicate the direction of energy flow.
Energy Absorbed: + charge moves from positive polarity toward negative
Energy Supplied: + charge moves from negative polarity toward positive

4. Current Directions and
Voltage Polarities

5. Applications of KCL

6. Applications of KVL

7. Basic Circuit Elements
Sources (voltage and current)
Independent sources
Dependent sources
Resistors
Capacitors
Inductors

8. Resistors Resistance opposes the flow of charge. Measured in ohms ()
1 ohm = 1 volt / amp

9. Resistors
 = resistivity of the material

10. Resistivity

11. Resistors in Series R1 R2
EQUALS
R1 + R2

12. Resistors in Parallel R1 R2
EQUALS RT

13. KCL, KVL, and Ohm’s Law

14. Let’s Solve Some Circuits!

15. Let’s Solve Some Circuits!
Vs = 10 V R1 = 50  R2 = 150 

16. Let’s Solve Some Circuits!

17. Let’s Solve Some Circuits!

18. Let’s Solve Some Circuits!
Let’s write the KCL equations for all the nodes.

19. Let’s Solve Some Circuits!
Let’s write the KVL equations for all the loops..