if a hole is made on the upper end of a mercuary barometer dippedd. vertically in a mercuary cup what will be the effect on the mercuary
Answers
In a mercury barometer, if we make a hole in the portion above the level of mercury, then the mercury level in the column drops and ultimately all the mercury in the column goes into the reservoir below or if it's capacity is not large enough it overflows
Answer:In a mercury barometer, if we make a hole in the portion above the level of mercury, then the mercury level in the column drops and ultimately all the mercury in the column goes into the reservoir below or if it's capacity is not large enough it overflows.
The following image shows a different situation, when we make a hole below the level of mercury in the column:
enter image description here
The pressure at A
is zero and it gradually increases as we move down the column. The pressure at C and D are same as they are in the same horizontal level, and it is equal to the atmospheric pressure Patm From this reasoning, we can say that the pressure at B is lesser than Patm
.
So, I concluded that the mercury doesn't come out through this hole.
But, what will happen after this step? The reason, why I got this doubt is described below:
We know from Pascal's Law that a pressure applied to a particular section of a fluid gets transmitted to all regions without any loss. Before we made the hole, the force exerted by the mercury column at B
was balanced by the contact force provided by the walls of the column. But, after we make a hole, the force exerted on the hole by the atmosphere is larger than the internal force. So, the pressure at all the points within the fluid must increase by Patm
.
Will the level of mercury in the column rise above A
? Will it eventually touch the topmost part of the vertical column, as pressure at the topmost level of mercury must increase by Patm which was initially 0
? What will happen to the mercury in the reservoir? Will all the mercury in it will be sucked in by the column till the mercury level touches the upper part of the column? Doesn't this seem counterintuitive?
Kindly explain what will happen to this system. Is it correct to apply Pascal's Law in this way? Are my reasonings correct
Explanation: