physical properties of non metals

. where r , called resistivity is a property of the material and depends on temperature and pressure. Electrical resistivity of substances varies over a very wide range. Metals have low resistivity, in the range of 10 - 8 W m to 10 - 6 W m. Insulators like glass and rubber have ..

Forces at a distance Are equal and opposite. Depend upon the distance between the two objects. Depend upon the medium between the two objects for electrical and magnetic forces but not gravitational forces. Forces are described in different names. Some forces are shown in the following d..

A solid has certain characteristics: According to modern theory, the molecules of a solid are fixed in relation to each other. They vibrate in place, but do not wander around. This accounts for the fact that a solid keeps its own shape. Solids are usually crystalline. A solid is a crystalline subst..

Cathode rays travel in straight lines from the cathode to anode and cast shadow of the object placed in their path. (a) Cathode rays travel in straight lines. Cathode rays consist of an invisible stream of negatively charged particles. When the plates X and Y are given +ve and -ve potent..

In 1819, two French physicists Dulong and Petit discovered that the average molar specific heat at constant pressure for all metals, except the very light ones, is approximately the same and equal to nearly 25 J mole -1 o C -1 . Although the law is an approximate one, it conveys a very im..

It is believed that around 2000 BC the Chinese had already discovered the magnetic property of natural iron ore. In a part of Turkey formerly called Magnesia, there are deposits of an iron one which has the property of attracting iron. As this ore was discovered by Greeks they c..

The minimum amount of energy required to emit electrons from a metal surface is called the work function or threshold energy of that metal. The number of electrons emitted per second i.e. the rate of emission depends upon the material of the surface temperature of the surfa..

Introduction - In the chapter on current electricity, we had learnt about the flow of charges, conditions to produce the flow and how different materials respond to an external electric field. We had seen how materials are classified as conductors and insulators. In this chapter, we will study a ne..

Temperature Dependence of Resistivity - The resistivity of a metallic conductor nearly always increases with increasing temperature. As temperature increases, the ions of the conductor vibrate with greater amplitude, making it more likely that a moving electron will collide with an ion. T..

This heating is inevitable in any electrical circuit. Since the energy lost by the flowing charges ends up as disorderly thermal motion, the phrase 'ohmic dissipation' is also used to describe it. Often, this is an undesirable effect. For example, in electric circuits, the heat produced in a small ..