Question

The following figure shows two air-filled bulbs connected by a U-tude partly filled alcohol. What happens to the levels of alcohol in the limbs $X$ and $Y$ when an electric bulb is placed midway between the bulbs is lighted.

• A. The level of alcohol in limb $X$ falls while that in limb $Y$ rises
• B. The level of alcohol in limb $X$ rises while that in limb $Y$ fals1
• C. The level of alcohol falls in both limbs
• D. There is no change in the levels of alcohol in the two limbs

Answer 1

The correct option is A The level of alcohol in limb $X$ falls while that in limb $Y$ rises

The black colour being a better absorber of heat, bulb $\times$ gets more heated due to heat radiated by the electric bulb resulting in the expansion of air inside it. The expanded air requires more space and thus pushes the alcohol towards limb Y