 |
| Introduction |
|
| Very often, energy is generated at one place but consumed elsewhere. The transportation of energy from its source to the receiving end can be done in two ways: |
| |
 By actually moving the matter carrying kinetic energy and delivering it to the other end. |
| |
 By the vibration of the particles of a medium and thus, transferring energy from one particle to another. |
| |
| The following illustration will help us understand this better. |
| |
| Let two persons be positioned on the opposite banks of a small lake. If one person wishes to draw the attention of the other person, he can adopt any of the following methods: |
| |
 throwing a stone or shooting an arrow towards him |
| |
 shouting |
| |
 clapping |
| |
 waving a signal flag |
| |
 using a flash light |
| |
 creating ripples in water |
| |
| In the first method, he is transferring matter in the form of stone or the arrow. In all the other methods, energy is being communicated without the actual transfer of matter. In these methods, the energy is said to be transferred in the form of waves. Other examples of energy propagation by transfer of matter are |
| |
 Electric current in a wire |
| |
 Air currents set up by unequal heating of the surface of the Earth |
| |
 Ocean tides in which energy is transmitted by a fluid body |
| |
 Bullet fired from a gun |
| |
