2007PPP1Q27 brightness of bulb

Solutions: Option B

As lamp X is thicker and shorter, these two factors make the resistance of X lower than Y.

Recall: Length increases, R increases & cross-sectional area increases, R decreases.

[R = pL/A]

As both bulbs are connected to the same mains, (assume 240V), the potential difference across the bulbs are 240 V.

Brightness of the bulb depends on power, P = IV or V2/R, since V is constant, I across X is higher due to lower R,hence power of X is greater than power of Y, hence X is brighter.