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Question
Consider the barometer shown in the following figure. If a small hole is made at a point P in the barometer tube, will the mercury come out from this hole?
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Solution
Two pressures are acting upon point P:
(1) Pressure due to mercury level above point P equals to P1 (say)
(2) Atmospheric pressure = P0 (inwards)
And,
P0 > P1
As the inward pressure is more, the mercury will not come out of the hole.
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