Basic Laws of Electronic Circuit
IED12102
Basic Laws:
1. 2. 3. 4. 5.
Electronic terminology Series Circuits Parallel Circuits Ohm’s Law and dc Circuits Simple Electrical Diagrams
For single-source parallel networks, the source current (I ) is equal to the sum of the individual branch currents. s Is = I1 + I 2
For a parallel circuit, source current equals the sum of the branch currents. For a series circuit, the applied voltage equals the sum of the voltage drops.
V
V
In this first example, we will calculate the amount of current (I) in a circuit, given values of voltage (E) and resistance (R):
What is the amount of current (I) in this circuit?
©2004 Texas Trade and Industrial Education
Building Trades -Basic Electricity-Ohm's Law
15
In this second example, we will calculate the amount of resistance (R) in a circuit, given values of voltage (E) and current (I):
What is the amount of resistance (R) offered by the lamp?
©2004 Texas Trade and Industrial Education
Building Trades -Basic Electricity-Ohm's Law
16
In the last example, we will calculate the amount of voltage supplied by a battery, given values of current (I) and resistance (R):
What is the amount of voltage provided by the battery?
©2004 Texas Trade and Industrial Education
Building Trades -Basic Electricity-Ohm's Law
17
What if R=∞? i=0 The Rest of the Circuit + v –
i = v/R = 0
What if R=0? i The Rest of the Circuit + v=0 –
v=Ri=0
Kirchhoff’s Current Law (KCL)
sum of all currents entering a node is zero sum of currents entering node is equal to sum of currents leaving node
Kirchhoff’s Voltage Law (KVL)
sum of voltages around any loop in a circuit is zero
A loop is any closed path through a circuit in which no node is encountered more than once Voltage Polarity Convention
A voltage encountered + to - is positive A voltage encountered - to + is negative
I
Example 1: Determine current and source Since R3 and R4 are in
Basic Laws:
1. 2. 3. 4. 5.
Electronic terminology Series Circuits Parallel Circuits Ohm’s Law and dc Circuits Simple Electrical Diagrams
For single-source parallel networks, the source current (I ) is equal to the sum of the individual branch currents. s Is = I1 + I 2
For a parallel circuit, source current equals the sum of the branch currents. For a series circuit, the applied voltage equals the sum of the voltage drops.
V
V
In this first example, we will calculate the amount of current (I) in a circuit, given values of voltage (E) and resistance (R):
What is the amount of current (I) in this circuit?
©2004 Texas Trade and Industrial Education
Building Trades -Basic Electricity-Ohm's Law
15
In this second example, we will calculate the amount of resistance (R) in a circuit, given values of voltage (E) and current (I):
What is the amount of resistance (R) offered by the lamp?
©2004 Texas Trade and Industrial Education
Building Trades -Basic Electricity-Ohm's Law
16
In the last example, we will calculate the amount of voltage supplied by a battery, given values of current (I) and resistance (R):
What is the amount of voltage provided by the battery?
©2004 Texas Trade and Industrial Education
Building Trades -Basic Electricity-Ohm's Law
17
What if R=∞? i=0 The Rest of the Circuit + v –
i = v/R = 0
What if R=0? i The Rest of the Circuit + v=0 –
v=Ri=0
Kirchhoff’s Current Law (KCL)
sum of all currents entering a node is zero sum of currents entering node is equal to sum of currents leaving node
Kirchhoff’s Voltage Law (KVL)
sum of voltages around any loop in a circuit is zero
A loop is any closed path through a circuit in which no node is encountered more than once Voltage Polarity Convention
A voltage encountered + to - is positive A voltage encountered - to + is negative
I
Example 1: Determine current and source Since R3 and R4 are in