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Physics · Class 11

Lower a pressure probe

Mechanical Properties of Fluids

A deeper probe supports a larger liquid column and reads greater pressure. Density determines the slope. Container shape does not affect pressure at a given depth in the same connected liquid.

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Lower a pressure probe

திரவத்தின் ஆழம் அதிகரிக்கும்போது அழுத்தம் அதிகரிக்கும். ஒரே ஆழத்தில் அழுத்தம் பாத்திரத்தின் வடிவத்தைப் பொறுத்ததல்ல.

Key notes, relationships and model limits

Key relationship

p=pAtmosphere+ρgh; pgauge=ρgh.

Remember

A deeper probe supports a larger liquid column and reads greater pressure. Density determines the slope. Container shape does not affect pressure at a given depth in the same connected liquid.

Common trap

The pressure at the free surface is not zero when measured absolutely.

Model limits

Stationary incompressible liquid with a free surface at standard atmospheric pressure 101325 Pa; g=9.81 m/s².

What you will learn

Distinguish gauge and absolute pressure and predict their depth dependence.

Try the experiment

Try both scenarios, change one control, and predict the result before checking the graph and readouts.

Think of it this way

Change one input while keeping the others fixed, as you would in a controlled experiment.

Worked example

Absolute pressure at 2 m depth is 101325+19620=120945 Pa. Gauge pressure omits the surface atmosphere.

Why this matters

The model connects lower a pressure probe with an observable reading. Check the equation and assumptions before applying it.

Before you start

SI units · algebra · graph reading

Check your understanding

What gauge pressure is found 2 m under water?

Read the explanation

ρgh=1000×9.81×2=19620 Pa.

Course connection: Class XI Chapter 9. Consult the roadmap for CBSE, NEET, JEE Main and Advanced scope.