ELECTRICAL ENGINEERING
UNIVERSE Knowledge educational article.
Ohm's Law is one of the most useful first relationships in circuit analysis. It connects voltage, current and resistance and gives engineers a simple way to predict how a resistive element behaves under specified electrical conditions.
The relationship is V = IR. Voltage V is measured in volts, current I in amperes, and resistance R in ohms. Rearranging gives I = V/R and R = V/I.
For a fixed resistance, increasing the applied voltage increases the current proportionally. For a fixed voltage, increasing resistance reduces the current. This is a model of electrical behaviour rather than a universal description of every electronic device.
Suppose a 12 V supply is connected to a 6 Ω resistor. The current is I = 12/6 = 2 A. The resistor therefore carries 2 amperes under the stated conditions.
Electrical power is P = VI. Combining this with Ohm's Law gives P = I²R and P = V²/R. These forms are especially useful when selecting resistors and estimating heat generation.
An ideal resistor has a linear voltage-current relationship. Real components can depart from this model as temperature, material properties or device physics change. Diodes and many semiconductor devices are strongly non-linear.
Ohm's Law is a building block for analysing larger networks. Engineers combine it with Kirchhoff's laws, component models and measurement data to predict circuit behaviour and troubleshoot faults.