We will discuss about the conversion of energy from one form of energy to another form of energy.
Suppose, if we rub our palms they become warm. Due to rubbing our palms, the mechanical energy is converted into heat energy. Likewise, when two stones are rubbed sparks are produces.
When a workman rotates the sharpening wheel with his leg and places the edge of a knife or scissor on the wheel to sharpen. We see sparks which are produced due to friction.
1. Mechanical energy into heat energy
Here are some examples of conversion of mechanical energy into heat energy.
(i) When wood or coal is burnt in the hearth, heat is produced first and then light. Both heat and light energies are so closely related that the presence of one calls in the other.
(ii) When iron is heated, its colour changes from black to red and thus the heated iron beings to produce light. We know things become warm or even hot due to sunshine.
2. Electrical energy into heat energy
Here are some examples of conversion of electrical energy into heat energy.
(i) When electric current is passed through an electric heater, its wire is heated.
(ii) In an electric iron electrical energy is converted into heat energy and we can iron our clothes.
(iii) In an electric bulb, electrical energy is converted into heat first and then it begins to give light.
3. Mechanical energy into sound energy
Here are some examples of conversion of mechanical energy into sound energy
(i) When a batsman strikes a cricket-ball with his bat, a sound is produced and the ball goes away. Thus mechanical energy is partly changed into sound energy.
(ii) When a school-bell is rung, sound is produced. In doing so the mechanical energy changes into sound energy.