Question

The diagram shows a mercury barometer that is used to measure atmospheric pressure.
Which among the following distance decreases as the atmospheric pressure decreases?

Answer 1

Answer:

BD in the diagram decreases when the atmospheric pressure decreases.

Explanation:

➛ The length of the mercury will decrease to balance the decrease in the pressure due to atmosphere.

• As the atmospheric pressure is given by expression, P = h × ρ × g Thus, the decrease in the atmospheric pressure, will decrease the barometric height of the the mercury Barometer

• The barometric pressure changes which suggest that the air pressure also changes.

• If the barometric height is less than 76 cm, we can see the air pressure has fallen/decreased and if more than 76 cm we can say that the pressure and has increased.

• Let's see how it barometric height is affected by temperature. When the temperature of atmosphere rises, the density of air decreases. As the pressure of air is given by expression P = h × ρ × g, therefore atmospheric pressure decreases. Thus, barometric height recorded by parameter decreases. Converse happens in case of fallen temperature.

• So we conclude that when the atmospheric pressure decreases, barometric height recorded by barometer decreases.

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