Available online
Description
The programme has two main aims, firstly to show the significance of measurement in the philosophy of the T100 course and secondly to show how the problems involved in measuring to increasingly fi...ne tolerances are being solved. Since the programme accompanies the units on electricity and magnetism the examples of measurement problems and devices are selected from this subject area. The programme is presented by Professor John Sparkes and Dr David Blackburn.
The programme has two main aims, firstly to show the significance of measurement in the philosophy of the T100 course and secondly to show how the problems involved in measuring to increasingly fi...ne tolerances are being solved. Since the programme accompanies the units on electricity and magnetism the examples of measurement problems and devices are selected from this subject area. The programme is presented by Professor John Sparkes and Dr David Blackburn.
| Module code and title: | T100, The man-made world: a foundation course |
|---|---|
| Item code: | T100; 08 |
| First transmission date: | 05-03-1972 |
| Published: | 1972 |
| Rights Statement: | |
| Restrictions on use: | |
| Duration: | 00:23:30 |
| + Show more... | |
| Producer: | David Nelson |
| Contributors: | David Blackburn; Geoffrey Holister; John Sparkes |
| Publisher: | BBC Open University |
| Keyword(s): | Air frame; Dial Gauge; Fine tolerances; Noise; Problems; Signal averaging; Strain gauge; Transducer |
| Footage description: | G. Holister introduces the programme with a discussion on the need for measurements. He links degree of understanding of the environment with ability to take sophisticated measurements. As examples he cites 16th century explorers, Early trans-Atlantic airplanes, Trans-Atlantic jet flight, Landing on the moon. Still shots of each. Holister with a dial gauge. He measures stress on a beam in front of him and discusses the disadvantages of the dial gauge. Holister brings out a strain gauge. This instrument measures stress in a more sophisticated manner. He uses a large model of a strain gauge to explain how it works and shows that it is a transducer. Holister demonstrates the strain gauge on a beam. While doing so, he points out some of the advantages of the strain gauge over the dial gauge. Practical application of strain gauges is shown. The example is aircraft testing. Shots of different parts of an air frame being tested. D. Blackburn demonstrates several other types of transducers 1. Thermocouple; 2. Photocell; 3. Record player needle. (A diagram shows how the needle acts as a transducer). J. Sparkes sums up the measurement process with the aid of a diagram. Holister discusses sensitivity of different measuring systems. He explains what happens when a system is pushed to the limits of its sensitivity. He demonstrates by measuring a load on a beam with a strain gauge at 10x and then 100x normal sensitivity. At 100x unwanted signals begin to appear. Holister calls these signals noise. The nature of noise is discussed by Sparkes. His picture on the screen is distorted by electronic interference to demonstrate noise. Examples of several different types of noise are given. Shot of a radio telescope. Problem of eliminating noise from wanted signals is taken up. Measurement of a force acting on a suspension bridge which is being disturbed by traffic is used as an example. D. Blackburn describes two techniques, both using Signal Averaging, for solving this problem. Blackburn uses a model of a bridge which has a vibrator and strain gauge attached, to demonstrate one of the techniques for signal averaging. The signals together with noise are seen on an oscilloscope screen. They are unscrambled by an instrument which automatically carries out the signal averaging process. Holister sums up the programme. Credits. |
| Master spool number: | 6LT/70263 |
| Production number: | 00521_2531 |
| Videofinder number: | 2152 |
| Available to public: | no |
