Question

Suppose the pressure at the surface of the mercury in a barometer tube is P₁ and the pressure at the surface of the mercury in the cup is P₂.

(a) P₁ =0, P₂ = atmospheric pressure

(b) P₁ = atmospheric pressure, P₂ =0

(c) P₁ = P₂ atmospheric pressure

(d) P₁ = P₂ =0.

Answer 1

Answer:

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Answer 2

In Barometer tube, at the top of mercury, there is no air, which means there is an vacuum.

Now, In Vacuum, there is no pressure.

Hence, pressure at the top of mercury in Barometer tube is 0.

Thus, P₁ = 0

Also, Pressure at the surface of the mercury in cup will be equal to the pressure exerted by the environment, because when it is kept in cup. there is not vacuum but there is an air.

Thus, P₂ = Atmospheric pressure.

Hence, Option (a). is correct.

Hope it helps.