Help!! Question... (1 Viewer)

[Gelapo]

-Why do FM waves produce greater sound quality than AM waves?
-and what do 'kHz' & 'mHz' (I think thats right) actually measure?
- how do the properties of oil-in-water & water-in-oil emulsions relate to consumer products.
-oh yeh, can sum 1 tell me what we're supposed to know about modulation of waves (& how much detailed knowledge do we havta know 'bout it?).
that's bout it, I would reeeellly appreciate an answer. Thanx & goodluck U all!

 

[swordfish]

I dont think you need to know why, just the fact that they do. I think its because of the way an FM wave is generated- changing the frequency does not affect the wave the same way that changing the amplitude does. It is much harder to change the frequency and it requires special equipment. While AM radio was introduced in America in the 1920's, the technology to produce FM radio waves was not able to be used until the 1930s.
AM radio waves produce good sound at night, as the ionosphere, which they are reflected off, lowers. AM radio is also better able to bend around large hills, buildings etc than FM so AM can provide reception to places that FM cannot. There are good aspects of both waves.
Anything to do with Hz is to do with measuring the wavelength. mHz is bigger than kHz.
As for the modulation of waves:
You don't need to know any details at all (check the syllabus) except for the results of the prac where you were required to show how waves can be modulated to carry different types of information. My teacher was slack on this one but you should have done it using a cathode ray oscilloscope and microphone. When you produce a high sound into the microphone, the wave is shown on the screen of the oscilloscope and it has a high frequency, etc. It was in the HSC last year. If you look at the exemplar answers in the BOS standards packages, they are all really brief and sketchy so you don't need to know that much.
Sorry about the long answer, hope that helps.

 

[swordfish]

Oh yeah, the 'water in oil and oil in water' question....
An emulsifier is useful in a consumer product, whether it is oil in water or water in oil, basically to improve the look and taste of the product. Emulsifiers allow margarine to be in the form of a spreadable block, and they allow salad dressings, mayonnaises etc to look better, without a film of oil separated from the other ingredients. Often, 'mouth feel' is improved, so the product effectively 'tastes better'. That's all i can think of but if any one has anything else to add, well, go ahead.

*Yay, notice i am now an 'assistant member', no longer junior, a few more posts and i will be executive!*

 

[jm1234567890]

http://www.boredofstudies.org/community/showthread.php?s=&threadid=11579

emulsions

 

[Karlee]

With oil in water, the water evaporates more readily, and has a cooling effect on the skin, eg. moisturising cream. And with water in oil, it has a warming effect, because it leaves a bit of an oily film, eg. sunscreen. I think that's right...

 

[swordfish]

yeah, i agree.

 

[Gelapo]

Thanx guys that helps alot