Physics 1001: Laboratory 3.

Standing Waves.

Your name/student number:_________________________________

Date:_________ Marker’s signature:______________ Mark:______

Pre-lab Question 1:

What is the wavelength of a sound wave of frequency 500 Hz in air (you will need to look up the speed of sound in air)? ________ m.

Pre-lab Question 2:

If a person inhales helium gas the sound of their voice changes quite dramatically. Why?

Pre-lab Question 3:

A shower cubicle measures 0.86x0.86x2.1 m. If you were to sing in this shower what frequencies will be amplified? (The amplified frequencies will correspond to the resonant frequencies of the cubicle, assume it acts like a pipe closed at both ends so there must be a node at both ends. Take the range of the human voice to be 130 to 2000 Hz.)

Part 1. Resonant frequencies of open and closed pipes.

Following the instructions in the lab measure the resonant frequencies of the tube open at both ends. You may not be able to fill all the spaces in the table, but should find at least five resonant frequencies. The frequency difference column should be filled with the differences between the resonant frequency you have just measured and the next lower resonant frequency.

Open tube resonant frequencies.

Divisions

Time / Division

Period (T)

Frequency (1 / T)

Frequency difference

By considering the differences between the resonant frequencies, construct a linear equation describing the resonant frequencies.

______________________________.

Again following the directions in the lab manual close one end of the tube and measure the resonant frequencies. Closed tube resonant frequencies.

Divisions

Time / Division

Period (T)

Frequency (1 / T)

Frequency Difference

As you did for the open tube, construct a linear equation describing the resonant frequencies of the closed tube. ______________________________.

Compare the equations you have determined