Energy and Waves

We are going to investigate a quantity that is conserved, energy. That is, the total energy in an isolated system does not change during any process that occurs in the system. Or if the total energy in a system does change, for example, if it increases, we find that the energy of the surroundings of the system decreases by the same amount! Therefore, the energy of the entire Universe is fixed; it has the same value at all times!

• 1- We will introduce systems and ways to store energy in a system (energy can belong to a system in different forms). We begin by making a connection between a familiar concept, force, and our new topic, energy. We will identify several forms in which energy can exist in a system. Then, we will investigate ways that energy can transfer into or out of a system, or transform within a system.

• 2- We will investigate the term transfer of energy by mechanical waves. Wave motion represents phenomena in which a disturbance propagates through a medium. The disturbance carries energy from one point to another. But there is no matter that moves over that distance. Sound waves, seismic waves, waves on stretched strings, and water waves are all produced by some source of oscillation. To understand how radio and television work, we must understand the origin and nature of electromagnetic waves and how they propagate through space. Light is a form of electromagnetic radiation and represents energy transfer from the source to the observer. our study of electromagnetic waves will be with electromagnetism and quantum physics (much of what scientists have learned about atomic structure has come from information carried by waves).

• 3- Optics is the study of the behavior of light and its interaction with materials. Many phenomena in our everyday life depend on the properties of light - When you watch a television or view photos on a computer monitor, The blue color of the daytime sky, You see your image in your bathroom mirror in the morning, If you wear glasses or contact lenses, The colors of a rainbow, If you have ever seen the colored circles of the glory surrounding the shadow of your airplane on clouds as you fly above them. The phenomena mentioned here have been studied by scientists and are well understood.