Kirchhoff 1st law or the junction rule: for a given junction or node in a circuit, the sum of the currents entering equals the sum of the currents leaving. This law is a statement of charge conservation:
The Circuit Diagram means:
I1 = I2 + I3
Kirchhoff's Voltage (2nd) Law: The sum of all the voltages around any closed path in a circuit equals zero.
From the circuit, apply Kirchhoff's Voltage (2nd) Law, we can calculate current:
100V = 100 I + 100 I I = 0.5 A
2-Resistors in Series and Parallel Circuits
Series circuits
A series circuit is a circuit in which resistors are arranged in a chain, so the current has only one path to take
Equivalent resistance of resistors in series : R = R1 + R2 + R3
Parallel circuits
A parallel circuit is a circuit in which the resistors are arranged with their heads connected together, and their tails connected together.
Equivalent resistance of resistors in parallel: 1 / R = 1 / R1 + 1 / R2 + 1 / R3
3-Capacitor Circuits
The relationship between the current flow and applied voltage is given by
The Energy stored in a capacitor is expressed in joules and given by
