In which 120-V light bulb does the filament have greater resistance: a 60-W bulb or a 120-W bulb? If the two bulbs are connected to a 120-V line in series, through which bulb will there be the greater voltage drop? What if they are connected in parallel? Explain your reasoning.

When the voltage across the elements in the circuit is constant, V²/R is used to calculate the power, according to the theory of circuits and power dissipation.

$P=\frac{V^2}{R}$

Because the resistance R is inversely proportional to the power consumed by the bulb, the higher resistance is for a lower power 60 W bulb. In series, both bulbs have the same current I.

According to ohms law (V = IR), the voltage drop increases as resistance increases, and since 60 W has a higher resistance, the voltage drop is across 60 W.

Both bulbs have the same voltage drop in parallel, and the voltage is 120 V.

Hence, when a 60 W bulb is connected in series, it has a higher resistance and voltage drop. Both bulbs have the same voltage drop of 120 V when connected in parallel.