ELECTRIC CIRCUITS: BASICS OF VOLTAGE AND CURRENT LAWS
- Electric circuits follow fundamental principles described by Ohm's Law, Kirchhoff's Voltage
Law (KVL), and Kirchhoff's Current Law (KCL). These laws help analyze and design circuits
by describing the behavior of voltage, current, and resistance.
1. Ohm's Law
Ohm's Law is the foundation for understanding electric circuits. It relates voltage (V), current (I), and
resistance (R):
V=I⋅R
Key Points:
V: Voltage (in volts, V)—the energy per unit charge driving the current.
I: Current (in amperes, A)—the flow rate of electric charge.
R: Resistance (in ohms, Ω)—the opposition to the flow of current.
2. Kirchhoff's Voltage Law (KVL)
KVL states that the sum of all voltages around any closed loop in a circuit is zero:
∑V=0
Explanation:
The total energy gained by charges from voltage sources equals the energy lost in resistive
components.
Voltage drops (−V) are subtracted, while voltage rises (+V) are added.
Application Example:
For a simple loop with a voltage source Vs, a resistor R, and a capacitor C:Vs−IR−VC=0
3. Kirchhoff's Current Law (KCL)
KCL states that the total current entering a junction equals the total current leaving it:
∑Iin=∑Iout
Explanation:
At any node (junction), the incoming current is distributed among the outgoing branches.
