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.

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Measuring the speed of light: results

Answers to questions

Q1. How does this result compare with the speed of light in air?

A1. The value for the speed of light in air is taken to be 3 x 108 m·s-1

Q2. Investigate the definition of the term Refractive Index and see whether you can calculate an approximate value for the expected speed of light along the fibre optic cable. (The Refractive Index of the polymer used is about 1.6)

A2. Refractive Index is defined as the ratio Speed of light in Air / Speed of light in the medium. In this case we have:
1.6 = 3 x 108/v where v is the speed in the fibre optic cable.
Hence v = 3 x 108 / 1.6 which gives 1.9 x 108 m·s-1
This is the value calculated from the experiment.


This experiment was written by the design team at Lascells Ltd.


  • 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.

  • 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.

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    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

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

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  • 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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