Lesson 4: Transformation of Energy

As previously mentioned, energy cannot be created or destroyed, it is transformed into other forms of energy.  

Energy transformation can be defined as: the processes where energy is converted from one form into another. 

For example, when a torch is switched on, the chemical energy in the batteries is transformed into heat and light energy. 

Figure 1:  The energy transformed when a torch is switched on.

When a vacuum cleaner is used, electrical energy is transformed into mechanical energy.  Vacuum cleaners are very noisy, and the motor will get hot after a few minutes of use.  Sound and heat energy are wasted.  

Figure 2:  The energy transfer in a vacuum cleaner.

Figure 3: A microphone does not transform electrical energy into sound energy as you may have thought.  It's the other way round!

Figure 4: Some further examples of energy transformation.

When you make a phone call, several energy transformations take place:

• Chemical energy stored in the battery is converted into electrical energy.
• The sound energy in your voice makes the air vibrate. Vibrating air carries the sound energy into the phone.
• The diaphragm in the mouthpiece microphone converts sound energy into electrical energy.
• The electrical energy travels from the phone, via exchanges, to your friend's phone.
• A diaphragm in the earpiece loudspeaker of your friend's phone converts the incoming electrical energy back to sound energy.
• The sound energy travels out from the earpiece into your friend's ear.
• Some of the electrical energy is also converted into heat and light energy. 

Figure 4: the energy transformation in a telephone.