Speakers are used you to listen to music on your phone, enjoy a film at the cinema or hear a friend’s voice over the phone.
Basically speakers convert electrical signal into an audible sound, speakers contain an electromagnet, a metal coil which creates a magnetic field when an electric current flows through it. Inside a speaker, an electromagnet is placed in front of a permanent magnet. The permanent magnet is fixed into position whereas the electromagnet is mobile. As pulses of electricity pass from the audio IC through the coil of the electromagnet, the direction of its magnetic field is rapidly changed. This means that it is in turn attracted to and repelled from the permanent magnet, vibrating back and forth.
The electromagnet is attached to a cone made of a flexible material such as paper or plastic which amplifies these vibrations, pumping sound waves into the surrounding air and towards your ears.
To reproduce all the different frequencies of sound in a piece of music faithfully, top quality speakers typically use different sized cones dedicated to high, medium and low frequencies.
Basically in mobile phone speaker contains the resistance value starts from 16 ohm to 32 ohm.
We can measure this value from multimeter continuity mode