# Water level measurement using Capacitive Sensor

## Title of the Experiment:

Water level measurement using Capacitive Sensor.

## Objective:

To find out the level of water using a capacitive sensor and compare the measured value and calculated value.

## Theory:

Capacitance level instruments operate on the basic principle of the capacitance of a capacitor formed by the sensor. A Capacitor is made up of two conductive plates which are separated from each other by die-electric. The capacitance value(C) directly depends on the plate areas(A) and the distance between the two plates.

So$$C=\epsilon A⁄d$$

Capacitive sensors use an alternating voltage which causes the charges to continually reverse their positions. The moving of the charges creates an alternating electric current which is detected by this sensor.

• ·        It is very sensitive type and no moving parts exposed to fluid.
• ·        It is suitable for continuous indication.
• ·        Probe materials for most corrosive fluids are available.

• ·        The performance of a capacitance probe is severely affected by dirt and other contaminates because the change the dielectric constants.
• ·        Probe length and mounting must suit the tank.
• ·        Changing the temperature, material changing can affect the capacitance.

## Working Formula:

$$C=\epsilon o \epsilon rA⁄d$$

Where $$\epsilon o$$ =absolute permittivity in vacuum space.

$$\epsilon r$$ =Relative permittivity in Medium.

d= Distance between the two plates.

A= Area of the Capacitance plate.

## Apparatus table:

 Sl.no Name of the Apparatus Quantity Maker’s name Specification

## Observation Table:

 Sl.No Capacitance Value Measured Value Calculated Value %Error

## Conclusion:

Through this experiment, we can measure the capacitance and notice the changing of value when the level of water changed. During this experiment we have noticed some issue:

• During this experiment, we change water many times so the die-electric medium sometimes may vary.
• The container should have the same dimension all the time.
• Sometimes it varies due to heating up the instruments.

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