Download Current Directions and Voltage Polarities

Current Directions and
Voltage Polarities
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Current Directions and
Voltage Polarities
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Electrical Systems
Current Directions
andI
Voltage Polarities
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
Current Directions and
Voltage Polarities
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Applications of KCL
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Applications of KVL
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Basic Circuit Elements
• Sources (voltage and current)
– Independent sources
– Dependent sources
• Resistors
• Capacitors
• Inductors
Resistors
Resistance opposes the flow of charge.
Measured in ohms ()
1 ohm = 1 volt / amp
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Resistors
L
R
A
 = resistivity of the material
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Resistivity
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Resistors in Series
R1
R2
EQUALS
R1 + R 2
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Resistors in Parallel
R1
1
1
1


RT
R1 R2
R2
EQUALS
RT
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KCL, KVL, and Ohm’s Law
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Let’s Solve Some Circuits!
Let’s find te voltage of the
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Let’s Solve Some Circuits!
Vs = 10 V
R1 = 50 
R2 = 150 
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Let’s Solve Some Circuits!
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Let’s Solve Some Circuits!
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Let’s Solve Some Circuits!
Let’s write the KCL equations for all the nodes.
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Let’s Solve Some Circuits!
Let’s write the KVL equations for all the loops..
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