# Why Does Voltage Drop Across A Resistor?

Voltage drop refers to the decrease in voltage or potential difference across a conductor or component in an electrical circuit. In a circuit with resistive components, the voltage drop across each component is directly proportional to the amount of current flowing through it and the resistance of the component.

One of the fundamental laws of electricity is Ohm’s law, which states that the current through a conductor between two points is directly proportional to the voltage across the two points, provided the temperature and other factors remain constant. This relationship is expressed mathematically as:

I = V/R

where I is the current, V is the voltage, and R is the resistance.

This relationship can be used to explain why voltage drops across a resistor. When current flows through a resistor, it encounters resistance, which causes some of the energy of the current to be dissipated in the form of heat. This energy loss is reflected in a decrease in the voltage across the resistor.

The voltage drop across a resistor can be calculated using Ohm’s law. For example, if a resistor has a resistance of 100 ohms and is connected to a voltage source that is supplying a current of 1 amp, the voltage drop across the resistor can be calculated as:

V = I * R = 1 amp * 100 ohms = 100 volts

This means that if the voltage across the resistor is measured with a voltmeter, it will read 100 volts.

It is important to note that voltage drop is not the same as power dissipation. Power dissipation refers to the amount of energy that is being dissipated in the resistor, while voltage drop refers to the decrease in voltage across the resistor. Power dissipation can be calculated using the equation:

P = V * I

where P is the power, V is the voltage, and I is the current.

In summary, voltage drop across a resistor occurs because some of the energy of the current is dissipated in the form of heat as it passes through the resistor. This energy loss is reflected in a decrease in the voltage across the resistor, which can be calculated using Ohm’s law. Understanding the relationship between voltage, current, and resistance is essential for designing and analyzing electrical circuits.