1. Ohm's Law :
Ohm’s Law is the most basic and important rule in electrical engineering. This law states that the current through a conductor is directly proportional to the voltage applied across it, and inversely proportional to the resistance of the conductor. Mathematically, it is expressed as V = IR, where V is the voltage, I is the current, and R is the resistance.

Example :
If a resistor has 20Ω resistance and a current of 3A flows through it, then
V = 20 x 3 = 60A

2. Kirchhoff’s Current Law (KCL) :
The sum of currents entering a junction = the sum of currents leaving the junction.
This law states that the algebraic sum of all the currents entering and leaving a node (a junction where multiple circuit elements are connected) is equal to zero. This means that the total current flowing into a node must be equal to the total current flowing out of the node.

Example :
If 4A and 2A enter a junction and two branches leave it, then the outgoing currents must total 6A (may be 3A + 3A, or 5A + 1A).

3. Kirchhoff’s Voltage Law (KVL) :
The algebraic sum of voltages around any closed loop in a circuit is Zero. In Shorts Energy gained = Energy lost.
This law states that the algebraic sum of all the voltages around a closed loop in an electrical circuit is equal to zero. In other words, the total voltage drop around a closed loop must be zero.