Understanding Electromagnetic wave

[asviron]

hai,

Can anyone help me to understand the electromagnetic wave ? I've compared basic wave theories from physical nature such as sound wave. When to different source of sound produced there is an inteference of the waves. Compared to electromagnetic wave, there are so many wave being created in different bandwidth. How different bandwidth ensures there no interference? This does not happen with sound wave, we are unable to seperate sound in the hearing field to select only specific source to be heard, imagine being in a large mall and we want to hear from one particular source. But in electromagnetic field it can be done, watching a specific channel only. Can anyone clarify this to me as I'm not a scolar in electronics ?

 

[elecbaba]

This does not happen with sound wave

Who says. They try with directional and parabolic mics.
http://www.instructables.com/id/Dollar-Store-Parabolic-Mic/
http://www.solorb.com/elect/misc/bige/

there are so many wave being created in different bandwidth.

A audio tone of certain frequency is different than random noise. There is difference between frequency and bandwidth. A tone decoder can detect certain frequency. Can you explain how sonar works? A bat can also analyse reflected sound. A radar based on ultrasonic frequencies.

**broken link removed**
http://askabiologist.asu.edu/echolocation

**broken link removed**
Elephant's big ears are not showpieces. They help in communicating three miles away at sunsonic frequencies.

we are unable to seperate sound in the hearing field to select only specific source to be heard

Yes, humans can appreciate and take pride being technical.

 

[asviron]

The interfearance i was enquiring was in comparison with electromagnetic waves. How electromagnetic wave there no inteference at all , is it because they are not in air ? I agree with you with devices we could seperate sounds but only through final output speakers. But in publics with natural things it is impossiable.

 

[jiripolivka]

The only difference between sound and electromagnetic wave is that sound waves are longitudinal and the elmag wave is made by charges oscillating normally to the direction of propagation.
Sound is an elastic wave, air or mass particles oscillate forward and backward. Without air or other material sound cannot propagate.
Elmag wave is generated by charges oscillating in a plane normal to the direction of propagation. Once the wave is radiated, it need no more charges or mass particles, so it does propagate in a vacuum.

Both types of waves exhibit the same interference properties like standing waves, focusing by reflecting or dispersing obstacles. We know how to perceive sounds but our senses cannot perceive elmag waves but the light. We use various instruments and devices to generate and receive the elmag waves. We use resonance to separate multiple waves carrying different information.

Learn more by reading the history of radio and television; best of all you can experiment with simple radio devices to see what can be done. Imagine that radio waves we can detect come from much farther space than optical telescopes can see.