TPR Science Workbook Chem Ps#70 q. 6

[superman3]

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I read the solution, but I'm not sure I really understand the answer, or how it was obtained, so anyone who has this book and understands the solution....feel free to chime in. It's probably really easy, but my brain does not want to cooperate.

 

[Ssina]

I got only 5 questions for that psg!!??

 

[superman3]

I got only 5 questions for that psg!!??

I have the 2003 edition, that might have something to do with it. It's the question about the color that should appear the most intense (and corresponds to a passage about vision, rods, cones, etc.)

 

[Ssina]

it's Psg#15 in the version I have then! (hopefully they don't have 2 passages about cones and rods in gchem!)

I originally thought it would Violet! But that has to do with frequency and energy, not the intensity.

So all you have to do is draw dashed lines straight down on the graph for each color in the answers: red, yellow, blue, and violet.... then read the percent of maximum light being absorbed (Y-axis) for each color B,G,R (where it crosses each lines).

Yellow ends up having the most intensity since the dashed line crosses the Red (around 80%) and Green (around 75%), which gives you the highest combined %maximum light absorption.... for whatever reason they summed it up (even though we are talking about %, which throw me off too) but it's saying cones essentially absorb 80% red and 75% green to give you yellow, where as for other colors you don't get this much intensity....e.g. violet turns out to be around 25% Blue!

hope that makes sense!

 

[Erythropoietin]

That's right, we have to add up to get the intensity (think about constructive interference when you have to add up the amplitudes, and how "intense" the waves become). You can directly relate intensity and amplitude...
Cones are in the retina and responsible for color. When cones are exposed to very intense visual stimuli, a negative afterimage will be formed. This is why you see dark spots when you look at the sun for a long time and then look at other places. After some time has passed, you start to see normal again because the cone cells stops sending high intensity visual stimuli to the brain; they return back to normal since you are looking away from the sun now.

Here's something from Wiki:
The Sun is informally designated as a yellow dwarf, because its visible radiation is most intense in the yellow-green portion of the spectrum and although its color is white, from the surface of the Earth it may appear yellow because of atmospheric scattering of blue light.

Hope this helpshttp://en.wikipedia.org/wiki/Sun#cite_note-NASA-Sun-13

 

[superman3]

Thanks alot to both of you guys! That makes much more sense. They should replace their explanation with yours. lol. Also, have to hand it to TPR for solid integration of topics in some of their passages. This passage managed to combine bio, chemistry, and physics concepts.

 

[Erythropoietin]

Thanks alot to both of you guys! That makes much more sense. They should replace their explanation with yours. lol. Also, have to hand it to TPR for solid integration of topics in some of their passages. This passage managed to combine bio, chemistry, and physics concepts.

It's not THIS particular passage only, they tend to do that with most of their passages, which is why I strongly recommend TPR over other materials

 

[MedPR]

This is kind of off topic, but you're using the 2003 TPRH Bio? I have a pre-new MCAT version as well (2006) and I'm a little concerned it won't be beneficial since the MCAT changed a bit since the TPR book was written.

Have you found your version to be useful?

Thanks!