human hearing range 20hz to 20khz, electricity frequency 50hz... then why can't we hear electricity...?

Answer 1

in cases mentioned above, frequency refers different meanings. in the case of sound frequency means no. of vibrations of a oscilating particle per second. you can find the equation of progressive waves(which sound is in fact) as below:

y=asin 2πft
here, y=displacement of the particle from the equilibrium position in any time t
f=frequency
t=time
a=amplitude

if you plot the practically achieved results of y against t you will find a sine curve, which approves the equation above.

now comes about frequency concerning electricity.it is a concept of A.C. current in fact which refers how many times electricity is changing its direction per second. you can find the term in the following equation:

E=E'sin 2πft
here,
E=electromotive force at any time t
f=frequency
t=time
E'=highest value of e.m.f.

this equation is supported by the graphical representation of E against t.

now, in both the cases we find frequency as a valid term but in different definitions and in different forms too. so their role is not the same too. again, sound is produced by vibration in the particles pf a medium where electricity is produced due to the flow of electron. and until there is no vibration in a medium we cant hear sound.

adding, electricity does not follwe wave properties where you know thaty sound is a form of power that is beared by waves. also we can say, sound is a form of power that awakens the power of hearing in our brains. but electricity is not capable of that.

also frequency used in other terms(light, simple harmonis oscilation) cant make us feel hearing that until it is turned into sound or in other words, until it vibrates the air particles around us.

Answer 2

Hearing involves vibration of a mechanical media in the frequency range you mentioned. Even though alternating current has a frequency ( and is measured in Hz also ), it may or may not have anything to do with mechanical oscillation. However, if the circuit is such that the alternating current generates vibration ( as in a speaker ), then you can hear the mechanical vibration, otherwise not.

You can ask a similar question -- Human eyes can see electro magnetic vibration in the optical frequency range , why can it not "see" the sound? The point again, there are vibrations of different kinds and different detectors for different kinds of vibration, even though the unit of frequency is typically Hz.

Answer 3

You can hear it, sort of. The hum of a transformer or the buzz of a fluorescent light (the regular old kind, not the new compact ones) is the same frequency as the electricity.

But electromagnetic waves are a different physical phenomenon than sound waves. Your ears cannot detect electromagnetic waves and your eyes cannot detect sound waves, no matter what the frequency is.

Answer 4

Logically speaking we shud be able to hear electricity.The wave form being in the frequency of about 50 hz.

But all electrical wires are covered with insulations.Apart from providing electrical insulation,it also serves as insulation to sound.As a result of which the vibrations are unable to leave the interiors of the insulation.

A very common example can be attributed to the large transformers whose working can be heard inspite of it being electric induced magnetic induction

Answer 5

Yes, andyoptic is correct. Transformers have iron laminations which are frequently imperfectly glued together. When the magnetic field in the transformer reaches a peak the laminations contract, and then it expands a little when the mag. field goes to zero.

The field reaches a peak for both positive and negative currents.

Thus the transformer is a type of speaker that radiates sound that you can hear. Because the laminations behave the same for both positive and negative currents, the sound you hear is 100 Hz sound (plus its harmonics) if you have 50 Hz electricity.

Answer 6

listening to selection frequently describes the form of frequencies which would be heard by ability of an animal or human, yet it could additionally consult from the form of stages. In people the audible selection of frequencies is frequently reported to be 20Hz to 20,000Hz (20kHz) (Hz is the standardised term for 'cycles in line with 2nd'), besides the shown fact that there is substantial version between persons, fairly on the severe frequency end, the place a delicate decline with age is seen common. Sensitivity additionally varies lots with frequency, as prepare by ability of equivalent-loudness contours, that are in many circumstances only measured for study applications, or specified study. recurring study for listening to loss frequently includes an audiogram which shows threshold stages relative to a standardised norm.

Answer 7

Well, because we only hear sound when the air vibrates. NORMALLY this does not happen with electrical supplies BUT you can hear transformers which hum because there is some magnetic induction to the metal casing, etc

Answer 8

Electricity is electromagetic energy. What we hear is acoustic energy (sound pressure changes). However, if you were to send the 50 or 60 Hz electrical current (at the right level--don't do this with household current!) to audio speakers, you WOULD hear it. It's the bane of the audio engineer: power-induced hum!

Answer 9

Well, because we only hear sound when the air vibrates. NORMALLY this does not happen with electrical supplies BUT you can hear transformers which hum because there is some magnetic induction to the metal casing, etc

Answer 10

20Hz - 20KHz is the frequency range of sound 50Hz is the frequency of electricity.

Answer 11

They're two different kinds of oscillations. Our ears detect the oscillations in our surrounding air pressure. The "frequency of electricity" usually refers to the frequency of the oscillation of the direction of current in an AC circuit. Basically, one measures air pressure, and one measures the flow of electrons.