No abstract

A ripple tank demonstration of the conditions for interference of waves Am.

Interplanetary magnetic fields and bulk plasma velocity values gathered by the Mariner 2 spaceprobe and corresponding to the recurrent geomagnetic storm of October 7, 1962, have been compared to ground‐based standard magnetograms and micropulsation recordings. The results indicate that (1) high‐latitude micropulsation enhancements can sometimes be correlated to large changes in interplanetary fields, (2) these sharp changes in the interplanetary fields and their corresponding effects suggest an interplanetary field structure corotating with the sun, a possibility that is consistent with the Pioneer 6 results, and (3) extended periods of micropulsations as well as bay disturbances are preceded and accompanied by exterior fields having a southward component. These results may provide support for Dungey's theory of reconnection between geomagnetic and interplanetary lines of force.

Articles on simple laboratory exercises in statistics have appeared in recent issues of the American Journal of Physics. This paper describes a similar experiment (but with a somewhat different pedagogic approach) which was introduced three years ago at the very beginning of an undergraduate laboratory course in physics offered at the Vidyodaya Campus of the University of Sri Lanka. An important feature of the exercise to be discussed is that students verify empirically the various aspects of the Gaussian distribution. They obtain a working knowledge of, and a confidence in, some of the commonly used simple statistical procedures, and in particular they are introduced to the sampling technique.