Measuring speed of EM waves (1 Viewer)

[ReaL~]

Ok i've been revising for trials so far and i come across i2i topic
i understand that radio waves are produced by a oscillating spark and recieved on a reciever. But the thing that confuses me is how hertz measured the speed = c?
thx=]

 

[Forbidden.]

Ok i've been revising for trials so far and i come across i2i topic
i understand that radio waves are produced by a oscillating spark and recieved on a reciever. But the thing that confuses me is how hertz measured the speed = c?
thx=]

LOL I thought you knew how to do this in the Preliminary course, nonetheless I will remind you.

f = Hertz (frequency)
t = seconds (time)

To measure frequency simply divide 1 by the time i.e f=1/t
Frequency is the reciprocal of time

To measure frequency simply divide 1 by the frequency i.e t=1/f
Time is the reciprocal of frequency

I thought ALL EM Waves travel at 3x10⁸ ms^-1

c is a constant for the speed of all EM waves, you know c = f*λ don't you ?
Where speed of EM waves is equal to freqency multiplied by the wavelength

So a 100 Hz wave will have a wavelength of 3x10⁶ ms^-1 = 3x10⁸ ms^-1 ...

 

[ReaL~]

haha thx =]
But still doesn't help me LOL
im stuck on the bit with the . Where hertz uses a mirror to reflect interference and . .. thats wher ei got stuck
sorry about that =)

 

[alcalder]

OK, so Hertz used those equations to find the speed of the wave.

c=fλ

But to find c, he needed to know both the freuqency, f, and wavelength, λ of the wave (later known to be a radio wave).

Frequency was easy - he set that. He then needed to measure the wavelength and this he did using the interferometry experiment (just like Michelson-Morley but using a metal plate to reflect the wave, not a mirror).

Essentially, one radio wave travelled directly to the source and another wave was reflected from the metal plate and produced an interference pattern. The wavelength of the wave can then be determined by analysing the intereference pattern. You don't need to know how that analysis is done, but if you want to know I can post it up for you.

Does that help?

 

[ReaL~]

wow! your explanation is so much easier to understand then the textbooks!

THX

 

[Forbidden.]

OK, so Hertz used those equations to find the speed of the wave.

c=fλ

But to find c, he needed to know both the freuqency, f, and wavelength, λ of the wave (later known to be a radio wave).

Frequency was easy - he set that. He then needed to measure the wavelength and this he did using the interferometry experiment (just like Michelson-Morley but using a metal plate to reflect the wave, not a mirror).

Essentially, one radio wave travelled directly to the source and another wave was reflected from the metal plate and produced an interference pattern. The wavelength of the wave can then be determined by analysing the intereference pattern. You don't need to know how that analysis is done, but if you want to know I can post it up for you.

Does that help?

I am still doing the Preliminary Physics course, and I think you did HSC Physics before so you are more capable of explaining this.