Table of contents

An apparatus for simulating centrifugal forces on an overhead projector is described. It enables students to concentrate their attention now on one (the accelerating), now on the other (the inertial) frame of reference, more easily.

A very simple device which is easy to make and has proved invaluable as a 'universal' demonstration of multiple-beam interference effects is the Edser-Butler plate. Interference fringes are formed by multiple reflections in an air gap between two partially silvered glass surfaces and are viewed in transmission. The condition for constructive interference is given by the formula 2t cos theta =p lambda where t is the local gap thickness, theta the angle of incidence measured in air and p an integer.

The method depends on the existence of a driving force on a liquid dielectric in an electric field. The force leads to a rise in the liquid level between the plates of a capacitor. The capacitor plates were placed just above a reservoir of the dielectric liquid, the level of which was monitored by a travelling microscope. The rise in liquid level (h) was measured for selected values of voltage (v) until sparking between the plates occurred. A plot of h against V² was obtained, and the dielectric constant was determined from the slope of the graph.

A study was carried out to investigate whether there are any conditions consistent with the laws of physics in which a hockey ball could strike a goal post, score a goal and return to the field of play without the intervention of a player. The analysis is within the compass of elementary undergraduate mechanics (and some sixth formers) and provides a good example of the application of the physics of collisions to a real-life macroscopic example.

A derivation of the approximate relation y_R approximately=Ls/dx Delta V/V (1+eV/2mc²)=Y_c(1+eV/2MC²) between the relativistic (R) and classical (C) prediction for the deflection of an electron (mass m, charge -e) entering (with kinetic energy eV), a transverse electric field of strength 2 Delta V/d and effective length s, is demonstrated. A coordinate system was chosen which has the y axis antiparallel to the field and the axis along the initial velocity. Thus the problem is essentially two-dimensional.

Some of the issues involved in setting up a computer assisted learning (CAL) system are discussed, and the way in which the CUSC project (Computers in the Undergraduate Science Curriculum) has dealt with them is described.

A list of stamps relating to physics issued between the 1976 and 1977 Gibbons Stamps of the World Catalogue

Two of the calculations with which many students involved with position-finding have difficulty are the interconversions between sidereal and solar times and between celestial and terrestrial coordinates. The author describes how these calculations are aided by the use of spherical polar and stereographic projections. The methods have limited accuracy but are quick and simple and reinforce understanding of the concepts involved.