A 630 W bulb and a 315 W bulb are both designed to operate at standard household voltage of 120 V. Determine which bulb has the lower filament resistance and then calculate the value of its resistance.

630 W bulb has lower resistance than 315 W bulb

Explanation:

The resistance of the bulb can be found using the operating voltage of the bulbs and their wattage.

As we know from Ohm's law

V = IR

I = V/R

Also power is given by

P = VI

P = V * (V/R)

P = V²/R

R = V²/P

For Bulb 1:

R = 120²/630

R = 22.85 Ω

For Bulb 2:

R = 120²/315

R = 45.71 Ω

Therefore, the bulb with a higher wattage of 630 W has lower resistance than the bulb with a lower wattage of 315 W.