# Electrical Power Calculation: Ohm's Law and Resistance

## What is Ohm's law and how can it be used to calculate resistance?

By using Ohm's law, what is the resistance of a 100-W light bulb connected to a 110-V source?

## Understanding Ohm's Law and Resistance Calculation

Ohm's law is a fundamental principle in electricity that relates the voltage (V), current (I), and resistance (R) in an electrical circuit. It states that the current flowing through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance.

When calculating the resistance of a 100-W light bulb connected to a 110-V source, we can use Ohm's law formula: R = V/I.

## Explanation of Ohm's Law and Resistance Calculation

Ohm's law is represented by the formula: V = I * R, where V is the voltage in volts, I is the current in amperes, and R is the resistance in ohms. To calculate the resistance of a device, we rearrange the formula to R = V/I.

In this scenario, the voltage of the source is 110 V and the power of the light bulb is 100 W. We first need to calculate the current (I) flowing through the bulb using the formula P = V * I, where P is power in watts. We rearrange the formula to find I: I = P/V.

Plugging in the values, we get: I = 100 W / 110 V = 0.91 A.

Next, we will use Ohm's law to find the resistance R. Rearranging the formula V = I * R to R = V/I, we get: R = 110 V / 0.91 A = 121 ohms.

Therefore, the resistance of the 100-W light bulb connected to a 110-V source is 121 ohms.