Asking the distributed mind

[redbird]

I'm trying to figure out what needs to be in one of the high school review/test prep books we're doing. Mostly it's going okay--sometimes frustrating, but I know what they want and can therefore figure out how to cover it. This is an exception.

The Illinois high school science standard says "Understand the reflection, refraction, diffraction, interference, and frame of reference properties of waves." All clear except for the last phrase.

My best guess is that they want students to know that the speed of light doesn't change depending on your frame of reference. Can anyone confirm that or show me that I'm on the wrong track here.

Googling isn't much help, it mostly gets me either odd question/discussion forums or sites connected to Illinois school, just quoting the wording of the standard.

Comments

[adrian_turtle]

"Frame of reference" does not just refer to the speed of light, but to any kind of wave. Violin strings, water, springs, air... They probably want students to have at least some vague awareness of what's moving, and in what direction, and know the difference between transverse and longitudinal waves. I'm not sure if that's implied in the standard.

Of course, the big implication of frame of reference for waves is the Doppler effect. They *definitely* want students to understand the principles behind that, for both light and sound.

[ellarien]

I wonder if they're thinking of Doppler shift? Perceived wavelength changes depending on motion relative to the observer; hence red-shift/blue-shift in astronomy, and also the change in pitch of sound from a passing train. It doesn't have to invoke relativity, though that can come into it. I don't think special relativity is high school level stuff, or it wasn't in my day. (And in my day we started calculus in the equivalent of junior high.)

Note: I know nothing about Illinois high schools, but I am a trained physicist, and I can almost visualize my school exercise book with the little diagrams showing how that works.

[jerusha.livejournal.com]

Doppler shift is what I was thinking, too.

[bibliofile.livejournal.com]

This sounds reasonable to me. I took high school physics in an Illinois high school, but alas my notes and stuff are long gone. We spent a lot of time on Newton, though, and not so much on relativity IIRC.

[tiger-spot.livejournal.com]

Mm, yeah, Doppler shift sounds really plausible in context.

[redbird]

Thanks, everyone.

I didn't think of Doppler shift at first because there's an explicit mention of it in a different part of the standard, on astronomy and the red shift, but "they got redundant" seems a lot more plausible than anything relativistic given that they aren't even expected to know trigonometry. (There is an odd mention of the "difference" [sic] between inertial and gravitational mass, but the sample test question makes clear that what they are expected to know is that these will give the same value.)