Table of contents

The author presents an analysis of 178 students who left Solihull Sixth form College between 1975 and 1981 to do a degree in physics (approximately one third) or engineering (approximately two thirds) at university or polytechnic. The first table is an analysis of physics A-level grade and degree performance; the second table an analysis of the points total for physics A-level plus maths A-level (five for A, four for B, etc.), against degree performances, and the final table an analysis of the points total for physics A-level plus maths A-level plus third A-level (again five for A, four for B, etc.), against degree performance.

Information plays an important role in the natural and technological environment. The authors show how the concept of information can play a major role in the structure of a middle or high school physics course. With the help of the concept of 'information carrier', this course represents an extension of an analogously-structured course for beginners based upon the concepts 'energy and energy carrier' introduced in a previous article, 'Energy and its carriers' (ibid., vol.17, p.212, 1982).

For pt.I see ibid., vol.20, p.124 (1985). In part I thought experiments (TES) were referred to as experiments which, although easy to conceive of are either very difficult, very expensive or even impossible to carry out. Their rule in physics was reviewed during an exposition of highly regarded examples drawn from special relativity and quantum mechanics. During this Kuhn's two necessary attributes (Kuhn 1977) of a TE were evaluated: the first, that its conduct should involve the use of concepts within previously experienced or imagined situations, was largely supported, although the possibility of inadequate application of the concepts was identified; the second, that the cognitive conflict which the TE provokes must have been anticipated in some way by the physicist, was not substantiated. As one major function of physics education is the development of future physicists, it is to be expected that TES have a substantial role in physics education. The authors explore some aspects of that role, drawing on examples from secondary school and tertiary educational practice.

The moving coil galvanometer is a linear second order system and many experiments have been described in which the galvanometer is used to illustrate the characteristics of such systems. With the advent of digital techniques and cheap computing facilities the tendency is for much simpler experiments to be performed in which the impulse response of the system is found and the transfer characteristics derived by computing the Fourier transforms of this impulse response. A special advantage of this approach is that amplitude and phase information are both available from a single measurement. The article describes an experiment for the undergraduate laboratory which demonstrates this approach. A moving coil galvanometer is the system under study and the EMF generated by the swinging coil provides the impulse response information in a form suitable for digitising and inputing to a microcomputer. The microcomputer can be used to display the digitised information and a simple discrete Fourier transform algorithm used to compute the frequency response. The results of the computation are available either in the form of the real and imaginary parts of the transfer function or as amplitude and phase data.

The author describes how, using an overhead projector (OHP) and a transparent roll of acetate film, it is possible to demonstrate travelling waves, standing waves and phase and group velocity applied to waves.

Sighted individuals take the eye and its processes very much for granted. Within this set of individuals there are many physics students who have little awareness of the optics of the eye. They are usually able to describe its basic structure and resemblance to a camera, and name some of its defects, but they seem to be unaware of the role of the various elements of the eye in the perception of spatial detail, i.e. visual acuity. To give a greater appreciation of human vision the author makes a comparison with other vertebrates and insects. Inevitably, in an article of this kind the picture must be incomplete, but the objective is to whet the appetite of the serious student and encourage him/her to research the subject more clearly.

The use of computers for monitoring and controlling experiments for educational purposes is discussed. The authors describe the hardware of the IMP, some of the devices it can be interfaced to, and the software support. Some of the experiments which can be performed using the IMP are described, including light intensity measurements of a mains filament lamp, control of the speed of an electric motor using a digital-analogue convertor, measurement of polar response of a small loudspeaker, pulse rate measurement and use as a firm of storage oscilloscope.

(1) A standing wave is produced whenever a wave is reflected back on its tracks. A resonant cavity requires a second reflection so that the twice reflected wave has the opportunity to be in phase with the original wave. Laser light is reflected from a mirror so as to return into the laser aperture and be reflected again from one of the mirrors surrounding the laser tube. A phototransistor attached to an audio amplifier gives a way of hearing what happens. (2) The early holograms available for schools give a virtual image when illuminated by laser light. The note describes how to change this to produce a real image. The laser is used to illuminate the hologram to produce a virtual image 'behind the hologram'. The light leaves the hologram as if it came from the virtual image. A pinhole camera effect is used to produce the real image.

When students are introduced to diffraction and interference in light, they are normally shown various qualitative demonstrations. In taking the subject a little further, there may be in practice a rather tenuous link between the diffraction patterns seen in the laboratory and the textbook graphs of intensity as a function of angle. The intensity must be measured at a series of positions using a sensor with a known response, and this can be a time-consuming and error-prone process. With an appropriate transducer, a microcomputer may be used to record light intensity. The author describes an arrangement whereby an interference or diffraction pattern may be scanned and the intensity distribution graph displayed, this graph being gradually revealed as the sensor traverses the pattern.

Gives a useful demonstration of the forces experienced by charged carriers, is a way of measuring the strength of magnetic fields and provides a means of determining important electrical parameters for conductor and semiconductor materials, i.e. charge carrier density and carrier mobility. It is therefore ideally suited to demonstrate a controlled system for the measurement of certain solid state properties of electrical conductors. It also demonstrates a way in which a physical effect can be used to produce an instrument which can provide a continual readout of a physical parameter-in this case the strength of a magnetic field. The authors used the Unilab Hall effect apparatus. A ZX81 is used to control the operation via a digital-analogue (DA), analogue-digital (AD) interface (ADA converter).

The authors present an experiment on the second condition of mechanical equilibrium. The first condition of mechanical equilibrium is that the vector sum of all forces acting on an object should be 0. The second condition is simply the ancient law of levers which was known to Archimedes. For a body in mechanical equilibrium the net torque taken with respect to any axis must also vanish. They begin by considering a weightless triangle V₁V₂V₃. By triangle they mean the boundary of the triangle together with its interior. The purpose of the experiment is to use the second condition of mechanical equilibrium to locate the point of concurrence of the three angle bisectors in an arbitrary triangle. Since each angle bisector is equidistant from the sides of its angle, the point of common to all three bisectors must also be the centre of the inscribed circle.