Light Bulbs. The power rating of a light bulb (such as a 100 W bulb is the power it dissipates

step 1 Okay, so we know power can be equal to potential multiplied by current. And current can be equal

Light Bulbs. The power rating of a light bulb (such as a 100...

Light Bulbs. The power rating of a light bulb (such as a $100 \mathrm{~W}$ bulb is the power it dissipates when connected across a $120 \mathrm{~V}$ potential difference. What is the resistance of (a) a $100 \mathrm{~W}$ bulb and (b) a $60 \mathrm{~W}$ bulb? (c) How much current does each bulb draw in normal use?

Key Concepts

Resistance Calculation Using Power Rating

The power rating of an electrical device indicates the amount of power it dissipates under a given voltage. By rearranging the formula for power (P = V^2 / R), one can solve for resistance as R = V^2 / P. This concept is essential for understanding how devices are designed and how their energy consumption relates to their electrical characteristics.

Current Calculation Based on Voltage and Resistance

Once the resistance of a device is known, the current flowing through it can be determined using Ohm's Law, expressed as I = V / R. This relationship allows for the calculation of the current draw from a voltage supply, which is critical for designing circuits and ensuring that components operate within safe limits.

Ohm's Law

Ohm's Law is a foundational concept in electrical circuits, stating that the voltage (V) across a resistor is equal to the product of the current (I) flowing through it and its resistance (R). This relation, expressed as V = IR, is crucial for analyzing how changes in voltage or resistance impact the current in a circuit.

Electrical Power in Resistive Circuits

In electrical circuits, power (P) dissipated by a resistor can be calculated using the formula P = V^2 / R, which relates the power to the potential difference (voltage) and the resistance. This formula is pivotal for determining how much energy per unit time is transformed into heat or light in devices like light bulbs.

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