The idea that light travels in straight lines is uppermost, while its wave character and other physical aspects are disregarded. Since the laws of reflection and refraction corollaries of the wave nature. Sources of light, such as the sun, stars, and electric lamps can be seen when the light they produce reaches the eyes. However, … Read more
What is Radioactivity? Radioactivity is the process of spontaneous disintegration of certain (unstable) atomic nuclei accompanied by the emission. Radiation is emitted by the unstable and exciting nuclei that can normally cause ionization in a matter through which they pass. These radiations can cause extensive. damage to the molecular structure of a substance either as … Read more
Transmission of Heat Heats are transferred from one region to another in three ways. They are conduction, convection, and radiation. ♦ Conduction When one end of a metal rod is heated, the unheated end soon becomes warm. This is because heat travels through the metal by the process of conduction. All electrons are constantly vibrating … Read more
Learning Objectives On completion of this lesson, you will be able to learn- ♦ x-rays ♦ properties of X-rays ♦ uses of X-rays ♦ bad effects of X-rays. Historical Background of X-rays In 1895, W.K. Rontgen a physicist at the University of Wurzburg in Germany was studied cathode rays in his laboratory. He was using … Read more
Several thousand years ago it was recognized that hot baths were therapeutic. Hot baths, hot packs, electric heating pads, and occasionally hot paraffin applied to the skin heat the body by conduction. Conductive heating is used in treating conditions such as arthritis, neuritis, sprains and strains, contusions, sinusitis and back pain. Radiant heat is also … Read more
Heat is gained by metabolism. Without loss of heat normal metabolism would increase the body temperature by 10C every hour. To a lesser extent, heat is gained from a hot environment and from eating hot food and drinks.
Heat is lost from the body via the skin, lungs and excretions. The most important route of heat loss is via the skin. Depending on external and internal circumstances, about 85 percent of heat loss occurs in this way. The average heat loss of the average male adult is equivalent to that of a 60-watt … Read more
Heats are transferred from one region to another in three ways. They are conduction, convection, and radiation. ♦ Conduction When one end of a metal rod is heated, the unheated end soon becomes warm. This is because heat travels through the metal by the process of conduction. All electrons are constantly vibrating and in metals … Read more