The following figure shows two air-filled bulbs connected by a $ U-$ tube partly filled with alcohol. What happens to the levels of alcohol in the limbs $X$ and $Y$ when an electric bulb placed midway between the bulbs is lighted
AThe level of alcohol in limb $X $ falls while that in limb $Y$ rises
BThe level of alcohol in limb $X$ rises while that in limb $Y$ falls
C
The level of alcohol falls in both limbs
D
There is no change in the levels of alcohol in the two limbs
Medium
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AThe level of alcohol in limb $X $ falls while that in limb $Y$ rises
a (a) Black bulb absorbs more heat in comparison with painted bulb. So air in black bulb expands more. Hence the level of alcohol in limb $X$ falls while that in limb $Y$ rises.
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