Q. A U-tube is partially filled with water. Oil which does not mix with water is next poured into one side until water rises by 25 cm. On the other side, if the density of oil be 0.8, the oil level will stand higher than the water level by
A) 6.25 cm
B) 12.50 cm
C) 31.25 cm
D) 62.50 cm
Explanation
(b) As the water level rises in one arm; it falls in another arm by 25 m. Equating the pressure at depth 50 cm down in arm of water with other due to liquid, we have $h \times 0.8 \times g = 50 \times 1 \times g$
Or $h = 50/0.8 = 62.5$ cm
Height of oil in one limb above the water in another limb
$= 62.5 - 50 = 12.5\ cm$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.