Ohm’s and Kirchhoff's Laws

Resistors:

• A resistor is a circuit component that dissipates electrical energy (usually as heat).
• Real-world devices that are modeled by resistors: glowing lights, warming components (stoves, radiators, and so on.), long wires.
• Parasitic Resistances: Many resistors on circuit diagrams model undesirable resistances in transistors, motors,etc.
• Resistance is measured in Ohms.

Ohm's Law:

• Ohm's law, named after Mr. Georg Simon Ohm, who defines the relationship between power, voltage, current and resistance.
• The voltage across a resistor is directly proportional to the current flowing through it.

                 - Conductor is also known as resistor.

                 - An ideal conductor is a material whose resistance does not change with temperature.

                                  Voltage = Current * Resistance

                                            V = I * R

Importance of  Ohm's Law:

• Defines the relationship between power, voltage, current and resistance.
• These are the very basic electrical units we work with. The principles apply to a.c., d.c. or radio frequency. 

Ohm's Law Formula's:

• For Voltage: E (volts) = I (current) * R (resistance).
• For Current: I (current) = E (volts) / R (resistance).
• For Resistance: R = E / I

Kirchhoff's Law:

• Kirchhoff's law, named after Mr. Gustav Robert Kirchhoff, these laws allowed to calculate the voltages and currents in multiple loop circuits.
• The amount of current that enters a junction is equivalent to the amount of current that leaves the junction.

                     Current into junction = Current leaving junction

• Kirchhoff's Current Law and Kirchhoff's Voltage Law are fundamental properties of circuits that make analysis possible.

Circuit Topology:

1. A Node: Any point where 2 or more circuit branches are connected together.
2. A Branch: Represents a single circuit (network) element; that is, any two nodes.
3. A Loop: loop is any closed path in a circuit (network). It is said to be independent  if it contains a branch which is not in any other loop.  

Law's:

1. 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

     

      2. Kirchhoff’s Voltage Law (KVL)

       

          - sum of voltages around any loop in a circuit is zero 

Kirchhoff's Rules:

1. Junction Rule: At any junction (3 or more connections) the sum of all currents = 0, there can be no charge work at the junction.
2. Loop Rule: The sum of the potential differences over all elements around a closed loop must = 0