Question

In a functional siphon, water rushes from the reservoir to the siphon because the ______________.

• A. pressure in siphon is higher than atmospheric pressure
• B. pressure in siphon is zero
• C. pressure has no role in the phenomena
• D.
  pressure in siphon is lower than atmospheric pressure

Answer 1

The correct option is B pressure in siphon is zero

A fluid always flow from high pressure to low pressure.

When a U-tube shaped siphon is placed in the upside-down "U" format, one end of the U-tube is smaller than the other end. The smaller end is kept at the height and the bigger end is kept at the low surface. When the water is sucked from the larger end, it makes the low pressure inside the tube, which further forces the water to suck into the U-tube from the smaller end. Due to gravity, water inside the larger end always falls down and creates low pressure which is filled by the continuous suction of water.