pls explain (1 Viewer)

[konggo]

describe Hertz’s observation of the
effect of a radio wave on a receiver
and the photoelectric effect he
produced but failed to investigate

outline qualitatively Hertz’s
experiments in measuring the speed
of radio waves and how they relate
to light waves


identify Planck’s hypothesis that
radiation emitted and absorbed by
the walls of a black body cavity is
quantised

pls someone exapln thes dot points to me thanks

 

[FcUk]

Ok ill try to explain it without looking at notes i have just read ova it a fwe times yesterday so ill see what i can remember:

There is an induction coil which has a gap, when the coil is turned on a spark crosses the gap and at the same time emits electromagnetic waves. This sparks set up changing magnetic fields which is propogated as an electro magnetic wave. These emr's travel to the second loop and cause a spark in the gap of that loop too(look at a diagram in ur book to see what im talking about). hertz also noticed that teh gap in the detector could be made greater by shining UV light on it but was able to explain it. Hertz from his experiments proved that the reflected, refracted, speed = c etcc.... and these were radio waves

He measured the speed of these waves by timing how long it took to get from the induction coil gap to the detecting loop i think... this relates to light as they both travel at c

Classical physics couldnt explain the black body curve so quantum theory was proposed. this is where radiation is emitted in bundles of energy called quanta or photons of energy. Einstein later explained this concept in more detail

Please feel free to correct anythin i have said coz im only 70% sure its correct

EDIT: from what ashtor is saying im guessing(only guessing) that he superimposed both light and the emr and they produced constructive interference ? or doesnt that make sense haha

 

[ashtor]

he didnt time them to calculate the speed he used superposition principles...theres a thread on that in the general section but i didnt understand it completely...

 

[snoopwogg]

Yea lol... what he did was have a wire connecting the receiver and the transmittor, and found the wavelength of the wave superimposed by the radiation travelling thru the air and the one travelling through the wire, by using superimposition principles, like ashtor said, and then he worked out the frequency by measuring the frequency of the oscillating spark in the transmittor, and then by v = f x wavelength, he worked out c to be equal to c

 

[mr EaZy]

i understand how he got frquency but for lambda, ill just sday he superimposed the 1st and 2nd transmitted EMR. (i cant understand it in time )

 

[CrashOveride]

just say he reflected the generated waves off a metal surface and measured the wavelength of the standing waves set up by interference. by substituting this wavelength and the known frequency of the wave generator into the wave equation v=f.lambda, hertz was able to calculate the speed of the waves to be about 3x10^8 m.s-1 , approximately the same value maxwell had predicted for light earlier.. easy to memorise from csu =p

 

[nit]

You could also say he used Lloyd's mirror and interference patterns. Also, he in fact got an erroneous value for c because he didn't take into account resonance effects in his room. When his results were corrected for this, he approximately came out with Fizeau's 3.15x10^8m/s

 

[swabbster]

can someone explain to me the whole course as i dont know it, the exam should be alot of fun tommorow

 

[Komaticom]

You want us to explain the whole course? Surely you jest?