Table of Contents
How is vacuum created in barometer?
The mercurial barometer consists of a glass tube, sealed at one end and filled with pure mercury. After being heated to expel the air, it is inverted in a small cup of mercury called the cistern. The mercury in the tube sinks slightly, creating above it a vacuum (the Torricellian vacuum).
How does the Torricelli barometer work?
(The first barometer of this type was devised by Italian physicist and mathematician Evangelista Torricelli in 1643.) The barometer works by balancing the weight of mercury in the glass tube against the atmospheric pressure, much like a set of scales.
Why is there vacuum inside tube of barometer?
The top of the barometer is filled with nothing (vacuum) because the mercury must have the space to expand and contract without any other force affecting it; a gas or liquid in the top would have its own pressure against the mercury and give inaccurate readings.
What is Torricelli’s vacuum?
The vacuum formed when a long tube, closed at one end and filled with mercury, is inverted into a mercury reservoir so that the open end of the tube is below the surface of the mercury. It is named after Evangelista Torricelli, who was responsible for the design of the mercury barometer.
Is there vacuum in barometer?
A barometer stabilizes the mercury level in the glass tube that is sealed with the atmospheric pressure on the open mercury chamber. The top part of the barometer is filled with the vacuum because the vacuum must have enough space to expand and contract without any external force acting on it.
How will you show that there is vacuum above the surface of mercury in barometer?
The space above mercury is a vacuum. This can be shown by tilting the tube till the mercury fills the tube completely. Again when the mercury column becomes stationary, the empty space is created above the mercury column.
How does Torricelli make the barometer?
The first mercury filled glass tube was generally accepted to have been invented in 1643 by Torricelli, which became known as Torricelli’s mercury barometer. In this he produced a vacuum by filling a glass tube with mercury, inverting it and then submerging the open end in a vessel of mercury.
How was MMHG created?
In the 17th century, Evangelista Torricelli conducted experiments with mercury that allowed him to measure the presence of air. He would dip a glass tube, closed at one end, into a bowl of mercury and raise the closed end up out of it, keeping the open end submerged.
Why is pressure of vacuum needed in a simple barometer?
The top part of the barometer is filled with the vacuum because the vacuum must have enough space to expand and contract without any external force acting on it. If gas is present in the top part of the barometer then that gas will exert a force against the mercury and gives inaccurate readings.
Why is there vacuum above the level of mercury in mercury barometer?
When the finger is removed, the level of the mercury inside the tube drops until the pressure at the bottom of the column of mercury is equal to the pressure exerted by the surrounding air. Since no air was allowed to enter the tube, the empty space above the mercury column is a vacuum.