It is a well known fact that the Earth carries a net negative charge that produces a downward electrostatic field. The present experiment shows how this field can be measured with a Field Mill which has been constructed from components readily available in the Laboratory. In fine weather conditions a value of 120 (±10) V m[superscript -1] was…

Most people are familiar with arc discharges through the use of simple gas lighters within the home but corona discharges are not so common. This note presents students with three simple corona discharge experiments so that they can appreciate this form of electrical discharge. Firstly, one detects whether positive or negative ions are created;…

Resonant cavity perturbation as a means to measuring permittivity has been used since the early 1940s. It is attractive because it is non-contact, non-destructive and experimentally simple. Only recently, however, has the cost of a small analyser board become acceptably low that experiments can be carried out in schools and colleges. Using the TE…

Experiments with Lecher Lines have always been important in the physics curriculum for demonstrating standing waves and the important concept that waves can be guided as well as being emitted into space. A system operating at low power (less than 10 mW) and in the frequency range 300 MHz to 800MHz is described and the wavelength of the radiation…

Paramagnetic and diamagnetic materials are now generally known as the "Cinderella" materials of the magnetic world. However, susceptibility measurements made on these materials in the past have revealed many details about the molecular bonding and the atomic structure of the so-called "transition" elements. Indeed, the magnetic moment of neodymium…

One of the basic truths regarding energy conversion is that no thermodynamic cycle can be devised that is more efficient than a Carnot cycle operating between the same temperature limits. The efficiency of the Stirling cycle (patented by Rev. Robert Stirling in 1816) can approach that of the Carnot cycle and yet has not had the commercial success…

Great scientists in the past have experimented with coils and magnets. Here we have a variation where coupling occurs between two coils and the oscillatory motion of two magnets to give somewhat surprising results. (Contains 6 figures and 1 footnote.)

Archimedes (287-212 BC) is well known for his explanation of buoyancy, and in particular for his "eureka" moment. This experiment uses his density measurement method to find the purity of gold, and additional confirmation of the findings are given by x-ray fluorescence. (Contains 4 figures and 1 table.)