Ohm's Law is used to calculate the relationship between voltage, current, and resistance in an electrical circuit. It's essential for designing circuits, troubleshooting electrical problems, sizing components, and ensuring electrical systems operate safely and efficiently. Common applications include electronics design, electrical engineering, automotive systems, and household wiring.

Ohm's Law uses three basic units:

• Voltage (V): Measured in volts (V)
• Current (I): Measured in amperes (A)
• Resistance (R): Measured in ohms (Ω)

For small values, you might use millivolts (mV), milliamperes (mA), or kiloohms (kΩ), but always ensure your units are consistent when performing calculations.

You should use Ohm's Law whenever you need to relate voltage, current, and resistance in an electrical circuit. Common scenarios include:

• Calculating the required resistor value for a circuit
• Determining the current draw of a component
• Finding the voltage drop across a resistor
• Troubleshooting why a component isn't working properly
• Sizing wires and fuses for electrical systems

Ohm's Law is primarily applicable to ohmic conductors (materials that maintain a constant resistance regardless of voltage or current). It does not apply directly to:

• Semiconductors (diodes, transistors)
• Non-linear components (LEDs, thermistors)
• AC circuits with inductors or capacitors (without modification)
• Superconductors (which have zero resistance)

For these cases, more advanced electrical principles or modified versions of Ohm's Law may be required.