Working Principle of a Siphon
As Eeshan and his mother sat inside their house by the window watching the rain outside, Eeshan’s mother suddenly realised something. The tank they had to store the rain water was not big enough to store all the rainwater. They had one more tank that was empty at the moment but the full tank would be too heavy to move out of the way and replace with the empty one.
“We have to find a plumber to connect our tanks with a pipe for next time,” said his mother, sighing. Eeshan had a brainwave. He came back a few minutes later with a long reinforced rubber tube in his hand.
“We are going to use this tube to fill water from our main tank into the empty one,” Eeshan told his mother.
“Let’s go outside, I’ll show you,” Eeshan said. They went out to the tank. As his mother watched, Eeshan put one end of the tube into the almost-full tank and the other end to his mouth. Then using all his might, he took a deep breath in.
In a few seconds, water gushed up through the tube from the tank and into his mouth. Immediately, he took the end of the tube away from his mouth and put it into the empty tank. His mother watched in amazement as water continued to flow from the first tank to the second one.
“We studied this in physics class one day,” Eeshan said. “It’s called a siphon and it works because of atmospheric pressure. When I suck at one end of the tube, it creates a low pressure area inside the tube. Water then rushes into this low pressure area from the high pressure area inside the tank.
Once the flow has begun, it will continue as long as the inside end of the tube remains below the surface of the water. The flow can be cut off by raising the outside end of the tube above the level of the surface of the water in the second tank,” he said as they walked back into the house.
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