Hertz experiment. (1 Viewer)

[Petyo]

I'm sorry I know this is a very dumb question:
Hertz produce radio wave when he made an electric spark.
Why is that spark neccessary?

 

[Fortify]

Spark = Detection of EM waves.

 

[Fortify]

He measured the speed of these waves, observed their interference, reflection, refraction and polarisation. In this way, he demonstrated that they all have the properties characteristics of light.

Taken off Jacaranda.

 

[Petyo]

um..Is there a electromagnetic field already(in the setup)?

 

[Fortify]

um..Is there a electromagnetic field already(in the setup)?

No, there is no electromagnetic field.

So, an induction coil is connected to two spherical electrodes with a narrow gap between them (the transmitter). So the short pulses of high voltage to the spheres generated oscillating currents in the transmitter which generates EM waves of a specific frequency. So these EM waves are radiated as a result of the oscillation and hence acceleration of free charges in the loop.

 

[Petyo]

I mean if he set up a circuit with oscillating current he could still generate EM waves (without sparks)

 

[Fortify]

Yes, the sparks are there to show you that EM waves are generated. Otherwise how is he going to prove that EM waves are present during the experiment?

 

[Fortify]

Also don't forget that the interference, reflection, refraction and polarisation created different sparks.

 

[Petyo]

Yes, the sparks are there to show you that EM waves are generated. Otherwise how is he going to prove that EM waves are present during the experiment?

but isn't that it was known, by that time, that an oscillating current could generate EM waves right?

 

[Fortify]

but isn't that it was known, by that time, that an oscillating current could generate EM waves right?

True, I think the radiation generated by his device showed properties of interference, reflection, refraction and polarisation and this created different sparks which are properties which also exhibited by light.

 

[Petyo]

Those properties were proven in other experiments.
This experiment (using an induction coil and a spark gap) was to prove the existence of EM waves.

 

[killua_3]

how did hertz show that EMR is polar? i reckon the jacaranda book is just useless in this topic, they never really explain clearly how this or that works...

 

[helper]

Easiest explanation is looking at his receiving spark coil. It only would spark, if the two gaps (transmitter and receiver) were parallel.

 

[Petyo]

arrrrgh