In a circuit, Ohm's Law establishes a relationship between voltage, current, and impedance (or resistance). The formula for Ohm's Law is:
V = I * Z
Where:
V is the voltage across the circuit (in volts, V).
I is the current flowing through the circuit (in amperes, A).
Z is the impedance of the circuit (in ohms, Ω).
Impedance (Z) is a generalized concept that includes resistance (R) as well as reactance (X). Reactance is the opposition offered to the flow of alternating current (AC) due to capacitance or inductance in the circuit.
When the circuit consists only of resistance (a purely resistive circuit), the impedance (Z) is equal to the resistance (R), and Ohm's Law simplifies to the more familiar form:
V = I * R
This is the basic relationship between voltage and impedance (or resistance) in a circuit according to Ohm's Law. It explains how the voltage across a circuit is directly proportional to the current flowing through it, with the impedance (resistance in the case of purely resistive circuits) acting as the constant of proportionality. If the impedance or resistance changes, the voltage across the circuit will also change proportionally to the new current flow.