L

GROUP MEMBERS

NOR FAZREENA BINTI MA’AMOR

(D20101037526)

NURSYAKHILA BINTI ZAHARI

(D20101037523)

AYU NADIA BINTI MOHD ZAHID

(D20101037528)

SPEED OF SOUND

This experiment describes the useof the ADC -212 virtual oscilloscopeto measure the speed of sound.

SPEED

OF

SOUND..

Scientific concept :

The speed of sound is the distance

travelled during a unit of time by a sound

wave propagating through

an elastic medium.

In common everyday speech, speed of

sound refers to the speed of sound waves

in air.

However, the speed of sound varies

from substance to substance. Sound

travels faster in liquids and non-

porous solids than it does in air.

Last weekend, my family decide to go to Gua

Kelam in Perlis. As we walk through the cave there

is a lot of nice things to watch. Then, I notice

something interesting, when we talk in the cave, we

can hear our voice be reflect. We hear our own

voice echo. Why this happened? I also notice the

same phenomena occur when I talk in empty house

or when I shout in the tunnel. How can this happen

and what is the cause?

EMPOWER

Equipment required

2 microphones-crystal Mics were used since

they are cheap and give a large output

1 metre wooden rule

Fast digital storage oscilloscope-the ADC-212

was used

A balloon-to burst for a sudden loud sound

source

Experiment set upThe experiment was set up as shown below with two

crystal microphones placed 1 metre apart

Results :

The balloon was burst approximately 2 m away from the foremost Mic. The plot below shows the results clearly.

The lefthand “BLUE” trace is from the fpremost Mic(Mic 1) and the righthand “red” trace is from mic

( Mic 2)

The waveform from Mic 1 between -164µs and 500 s is clearly visible in the trace from Mic 2 delayed by 2929 µs. There is second variation , in the waveform from Mic 1, around 1.5 ms caused by an echo from one wall or ceiling.

ENHANCE

Telling how far away a person with a starter’s gun, at a running race, is by comparing the time difference from when you can see the gun’s smoke to when you hear the sound.

Telling how far away a cliff is by making a sound and measuring how long it takes for the echo to return

Telling where an enemies gun was fired.

Telling how far away a lighting strike.

THE END