2 answers to multiple choice? (1 Viewer)

[ladystar]

Ok I got no clue whether this is the right place to post but.. I'm curious what people thought, so.

HSC 2007.

Q10 multiple choice: What is the wave property that enabled Hertz to calculate the velocity of radiowaves and compare it to the velocity of light?

A) Interference
B) Polarisation
C) Reflection
D) Refraction


I don't think it's possible for him to have calculated the speed of radio waves without BOTH interference AND reflection. Think they had to be reflected along 2 different paths from the same source (thus reflection)...but he had to set up a standing wave to measure the wavelength or at least measure the distance between maxima and minima (thus interference) ..which was impossible without the reflection in the first place

In the end I put reflection coz I couldn't be bothered thinking about it any more - thoughts??

 

[danos0]

i thought the same

 

[twilight1412]

i say interferance because he measured the distance between the constructive interferance ...

there are more ways of doing it than reflection
ie he could have used diffraction grating and then measureed the distance between the constructive interference

 

[ladystar]

except for the fact that hertz didn't do that? (at least not from our sources)

wonder if you can measure wavelength with diffraction alone?

 

[mzduxx2006]

a)

 

[davidbarnes]

I'd go with A as well.

 

[rajeenth]

the answer is clearly d)

 

[Miroku]

I think it's interference. Because with only reflection he couldn't have measured the wavelength.
He knew the frequency of the wave (the supplied AC current frequency), so he measured the distance between the nodal points of the interfered waves and used the equation C=Velocity x wavelength to calculate the velocity.