## DrDAQ

#### Data logger, oscilloscope, signal generator and more!

DrDAQ is a versatile instrument that connects to the USB port of any PC. Using the supplied PicoScope software it can be used as an oscilloscope, spectrum analyzer and signal generator.

# Can your recorder tell you the speed of sound?: results

## Teachers’ notes

This is an activity from the AS unit The Sound of Music and is one of many looking at the physics of sound. It will probably be the first occasion that the students will have used the Spectrum Analyzer so an introduction to its use would be wise.

The microphone on DrDAQ data logger is ideally suited to this task. Needless to say, other recorders being played at the same time will also get recorded. The playing of a number of them needs to be controlled.

Additional frequencies could be obtained by the playing of a tenor or bass recorder.

If students are already competent with drawing best-fit lines and calculating gradients then they might like to use a spreadsheet here instead, the data collected being placed into one and the appropriate graph and best-fit line plotted.

## Answers to questions

1. Taking the speed of sound v to be constant, f will then be inversely proportional to l and so the graphs will be as in Figure T11.1

Figure T11.1: graphs of (a) f against l and (b) f against 1/l

2. Writing the equation as:

f = v/2 x 1/ l and comparing with y = mx + c the gradient must be equal to v/2.

The results obtained should compare very favourably, but there will be inaccuracies in the measurements of the length of the standing waves and in the precise value of the fundamental frequency as indicated by the spectrum analyzer.

The inability of the best-fit line to pass through the origin could best be explained by a consistent error in determining the length of the standing waves.

Figure T11.2: table of results

## Results

Note Frequency /Hz l /m 1/l m -1
C 536 0.326 3.07
D 607 0.279 3.58
E 686 0.253 3.95
F 747 0.234 4.27
G 809 0.210 4.76
A 926 0.187 5.35
B 1024 0.168 5.95

## Apparatus

• Pico DrDAQ
• PC running PicoScope
• Descant and other recorders
• Disinfecting solution
• 0.5 m or 1 m rule

Between use ensure that the mouthpieces of the recorders are disinfected.

## Testimonials

• The kit (2408B) is of obvious quality, easy to setup and calibrate and the free to download software has a reasonable learning curve. Superb kit, superb support, what more can I say.

Rop Honnor
• I have been using my 4224 PicoScope for years. I travel abroad so this has been ideal due to its physical size. Storage of waveforms on my Laptop is very easy allowing me to quickly email waveforms to my Colleagues.

Andrew
• Not many USB scopes works on Win & Mac & Linux too, so that proves me that guys from Pico really cares about us, customers. This made my decision much easier when I was looking to buy an USB scope.

Raul Trifan
• We have been using Picoscope 6404D for quite some time, and are amazed by its accuracy and powerful emulations while working with numerous signal evaluations.

J Mohanty
• PicoLog TC-08: This is a very nice unit that works consistently and reliably.

Jeff Hulett
• It is a great scope. I had a weird problem - it did not work on one of my PC’s. Customer service gave me first class service. If I could give 6 stars for customer service - I would do so.

Niels Larsen
• Perfect Partner for Development of Encoder controlled Stepper Motor Actuators. Since the included software is really stable, this type of device is a great tool for great tasks!

Helmut Schoettner
• A superb piece of equipment worth its weight in gold

Nigel Clinch
• So simple to use & beats any other I have ever used hands down.

John D Samsing
• Rather than webcam our benchtop scope screen, it was suggested we use a PicoScope to share waveforms via screen share.

We were a bit hesitant at first … but it worked flawlessly, and everybody is now out shopping for PicoScopes!

T Lövskog • SVP of Innovation at Additude AB
• Great functionality in a compact size. I really like moving the mouse pointer to a position and having the Time and Voltage display the values at that point. Calibration equipment is a breeze with that feature.

Don Horein

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