Question

To measure moderately low pressures oil with a density of 8.5 × 102 kg/m3 is used in

place of mercury in a barometer. A change in the height of the oil column of 1.0 mm

indicates a change in pressure of about:

A. 1.2 × 10−7 Pa B. 1.2 × 10−5 Pa C. 1.2 Pa D. 8.3 Pa​

Answer 1

To measure moderately low pressures oil with a density of 8.5 × 10² kg/m³ is used in place of mercury in a barometer. A change in the height of the oil column of 1.0 mm.

We have to find the change in pressure.

using formula, P = ρgh

• ρ is density of liquid oil.
• g is acceleration due to gravity
• h is height of oil column.

here,

• ρ = 8.5 × 10² kg/m³
• g = 9.8 m/s²
• h = 1mm = 10¯³ m

so, pressure = 8.5 × 10² × 9.8 × 10¯³

= 8.33 Pa [ nearest value of 8.3 Pa , option (D) ]

Therefore the correct option is (D) 8.3 Pa.