How does a microphone and speakers work ?

Today most of our electrical devices contains microphone and speaker. Our laptops, cell phone, alarms, clocks etc.

                           But how do these microphones/speakers work ?



Starting with the microphone.

Microphone - Simply speaking, it is an instrument for converting sound waves into electrical energy variations which may then be amplified, transmitted, or recorded.

Working of microphones can be explained in two ways - 

1. We have studied in class 10th that when magnet is moved inside or outside a solenoid is produces and an induced current(Faraday's law).
                                         
   
   Where induced E.m.f is given by-
                                            
   (Number of turns times rate of change of magnetic flux).
   
   Same goes with microphone.
   
   
   
   When we speak, we produce vibrations in air molecules, these vibrations are longitudinal waves with frequency range (20Hz - 20KHz). When they strike the diaphragm they let the magnet to move back and forth which produces current in coil (Faraday's law). And, current will have same frequency as that of sound wave you produce.
   So, you converted sound energy into electrical energy.
   
   
2. From Piezoelectricity -
   Piezoelectricity is the electric charge that accumulates in certain solid materials in response to applied mechanical stress. The word piezoelectricity means electricity resulting from pressure and latent heat.
   Some naturally piezoelectric occurring materials include cane sugar, quartz, Rochelle salt, topaz, tourmaline, and bone etc.
   
                                    
   
   

Now coming to the working of speakers -

Speaker - A loudspeaker is an electroacoustic transducer; a device which converts an electrical audio signal into a corresponding sound.

It's working is opposite of speakers.

When a current is passed through a solenoid the magnet inside will move back and forth which produces sound waves.

Construction of microphone and speakers are based on Faraday's law. If you know it well then you will grasp it quickly.