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…

An absorption line at 900 nm has been observed in Perspex. Samples of 1 and 2 cm thickness were used and the integrated absorption (line width times peak absorption) of the line was proportionate to the thickness. Facilities for lowering the sample temperature were not available and therefore both measurements were carried out at room temperature.…

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…