26 Radioactivity

This page covers the radioactivity section of the course. Take care not to mix units when calculating decay equations. For instance, you may encounter activities given in Becquerel’s and count rates stated in counts per minute; half lives are often quoted in reference works using the most relevant time unit, be it seconds or years.

Resources

26 Radiation Student Booklet

26 Radioactivity Part A (Lessons 1-4)

26 Radioactivity Part B (Lessos 5-9)

http://phet.colorado.edu/en/simulation/rutherford-scattering

Rutherford Alpha Scattering Experiment

Rutherford Scattering Experiement and results for A-level Physics and GCSE

Shows how alpha radiation will show the structure of the atom.

Rutherford Alpha Scattering Experiment

Rutherford Gold Foil Experiment - Backstage Science

3 Atomic Nucleus

Cloud Chamber Alpha Particles

Cloud Chamber and Alpha source.

Cloud Chamber Cosmic Rays

Protactinium half life experiment

GCSE Science Revision - Carbon Dating

The Oldest Mummy in the World - British Museum Gebelein Man

Gebelein, Egypt, Predynastic period, around 3500 BC

A naturally preserved mummy in a reconstructed pit-grave.

This man died more than five thousand years ago and was buried at the site of Gebelein, ...in Upper Egypt. The reconstruction of his grave illustrates the early Egyptian custom of placing the body in a contracted, foetal position, usually on the left side, with the head to the south, facing the west, the land of the dead where he would be reborn. Around him were all the things he might need for his afterlife, especially pottery to hold and serve food.

In the Predynastic period (4400-3100 BC), the time before the pharaohs, the dead were buried in shallow graves cut into the desert sand. The graves were often lined with reed mats, making them like a bed, and the body was covered with linen or skins and more mats, like a blanket, before the grave was refilled and perhaps topped by a mound of dirt. Contact with the hot dry sand naturally preserved the bodies because the sand absorbed the water that constitutes approximately 75% by weight of the human body. Bacteria cannot breed without moisture and as a result, the bodies frequently did not decay, but simply dried out. The body of this man is remarkably well-preserved, even down to his finger-nails and hair, which has probably faded with time.

Chance discoveries of these sand-dried mummies (for example, when a grave was disturbed by animals or robbers), may have promoted the belief that physical preservation of the body was necessary for the afterlife. This may have led the later Egyptians to develop means of artificial mummification after the introduction of coffins and deeper graves separated the body from the natural drying effects of the sand.

The objects that surrounded Gebelein Man in his original burial are unknown. On display is a selection of typical grave-goods from other graves of the middle Predynastic period (about 3500 BC), the time we believe he died. Attempts to date the body using Carbon 14 (the radiocarbon method) have so far been unsuccessfulShow More