Final answer:
The power rating of a light bulb, like a 100 W bulb, is the power it dissipates at a 120 V potential difference. Higher power rating means more light and heat due to higher current draw. Ohm's Law and the power formula relate voltage, current, and resistance to electric power.
Step-by-step explanation:
The power rating of a light bulb, such as a 100 W bulb, is a measure of the power the bulb dissipates, or consumes, when it is connected across a typical household voltage of 120 V. The power rating indicates the rate of energy use by the bulb. A bulb with a higher power rating, like a 60-W bulb compared to a 25-W bulb, will dissipate more power, giving off more light and also more heat because it draws more current. To find the relationship between voltage, current, and resistance in terms of electric power, we can use Ohm's Law and the power formula: Power (P) = Voltage (V) × Current (I), and Ohm's Law states V = I × Resistance (R), which allows us to relate these electrical quantities.
For example, finding the resistance of a typical incandescent light bulb that is rated at 60 W and connected to a 120 V supply involves using the power formula. First, we calculate the current (I) by rearranging the power formula as I = P/V. This gives us I = 60 W / 120 V, which is 0.5 A. Then, using Ohm's Law, we can find the resistance (R) by rearranging it as R = V/I, yielding R = 120 V / 0.5 A, which is 240 Ω (ohms).
Increasing the voltage beyond the bulb's design parameters results in a rapid increase in power, potentially causing the bulb to glow very brightly and then burn out, as would happen if a 25-W bulb rated for 120 V is connected to 240 V. The ratio of the resistances of different bulbs can also be calculated using the power and voltage values, which will be different due to their power ratings and voltage requirements.