Physical Health: Practicals

Three practicals produced by the Institute of Physics (IOP) that help students to understand some of the physics used in medical analysis. In addition to the guidance included for specific activities, please refer to the generic health and safety information before commencing any practical activity. This resource is accompanied by the Teacher and technicians' guide for both the practicals and activity sheets. [b]Radiography[/b] Students might work in small groups. The activity has several parts and might be best shared between 3-4 people. Students use light bulbs as an analogy to X-ray sources.They look at magnification, contrast and blur (the scientific term is spatial resolution - the smallest size feature that can be distinguished in the image). Formation of shadows using white light provides a useful analogy to X-ray image formation. The experiment might be carried out at two levels. It might be appropriate for students to comment qualitatively on the differences in magnification, contrast and blur. For other students, however, some quantification of the changes may be attempted. The key trends are: • Magnification depends on distance of phantom from the screen and the light source; the nearer to the light source, the greater the magnification. • Contrast depends on the nature of the light source (point light source is best) and the distance of phantom from the screen and the light source, the nearer to the light source, the less good the contrast. Also, the more similar the greyness of two phantoms, the lower the contrast in their images. • Blur depends on the same variables as contrast. Students might use mini-whiteboards to sketch ray diagrams to help explain their observations (qualitative or quantitative). [b]Make and use a spectropscope[/b] Students work as pairs in groups of four to make spectroscopes and use them to observe spectra. One pair makes the CD spectroscope and the other pair makes the DVD spectroscope.The two pairs come together to compare results. [b]Colour analysis in medicine[/b] This activity might be best undertaken by students working in pairs or small groups. Much will depend on the apparatus available. Pulse oximeters can be bought for £100-300.This may be expensive for a physics department, but other subjects may find it useful (e.g. biology, physical education) and the cost could be shared. If you can get one, its use would make an excellent introduction or conclusion to the activity.