Measuring the Depth of Water Using Sound Waves

Measuring the Depth of Water Using Sound Waves

Aim

The aim of my investigation was to create a sensor which could measure

the depth of water in a tank.

Plan

The way I proposed to measure the depth of water was using sound waves

which would be emitted and fired into the tank of water. The sound

wave should then be reflected of the bottom of the tank and picked up

by a microphone. The microphone would be linked to an oscilloscope and

the sound emitter would be linked to the oscilloscope. I would then

measure the phase difference between the waves. Then by changing the

depth of water in the tank, I would see what relationship would be

produced between the phase difference and water depth and test how

well the sensor worked.

Below is a circuit diagram which shows how I wanted to lay out my

investigation and the components involved:

The safety conditions I took into consideration when I did my

investigation were where:

* Be careful with all electrical equipment.

* Never touch electrical items with wet hands.

* If an accident occurs warn teacher immediately.

* Keep all items e.g. backpack out of peoples walking path.

* Always listen to what the teacher is saying.

* Keep round items and glassware which can roll firmly on the table.

Method

The method of my investigation was as follows:

1) I firstly set up the experiment as the diagram below shows:

2) I then used the loudspeaker which was connected to a signal

generator to produce a sound wave directly into the tank of water.

3) The reflected wave was then picked up by the microphone.

4) The loudspeaker was connected to one input of a CRO (cathode-ray

oscilloscope) and the microphone to the other. This allowed the

original sound wave from the loudspeaker and the reflected sound wave

picked up from the microphone to be shown on the oscilloscope screen.

5) I then calibrated the time base on the CRO so that both waves could