Suggested Solutions (VCAA Physics Unit 4 2008)

[We Want Peace.]

damn..i forgot that line below x axis should not be solid..

[hippo326]

huh anyone rmb the unit for plank's constant? i was like wtf

[champorado]

sida: less than me! :p

actually, how would that work? wouldn't it be weird having space for freq < 0?

[Nelle91]

Is discrete spectrum the same as line spectrum?

[amin_ali]

wat did question 15 in electric power ask i got 29.3 writin here for sum reason lol

[We Want Peace.]

the transformer thing.( study lamp)
they asked u to find the primary current.

[ilovevce]

Is it necessary to have the dotted line below the x-axis for the graph? I thought only the experimental values were meant to be graphed, not extrapolations. On one of the assessment reports it stresses not to extrapolate the solid line. I was tossing up between drawing a dotted line or no line. In the end I thought it would be safer to have no dotted line.

[ilovevce]

Question 1 2 marks
the key word here was "through the coil".... I wonder what they want... 5 lines towards the right, or 5 rings [because last year there was something in the ass report on this]. Go with your own interpretations.

Eek! They won't take marks away for drawing rings, surely? After all, part of the rings do go THROUGH the coil. I went to lots of effort annotating the rings to show their correct orientation, so it was obvious the lines come out of the page and to the right inside the coil.

[onlyfknhuman]

huh anyone rmb the unit for plank's constant? i was like wtf

hahahha me too i totally forgot THEN I LOOKED ON THE DATA SHEET AND THERE IT WAS

[pinchies]

Whoo-Hoo! Full multi!! (except debate over last one)

[onlyfknhuman]

fck bro, last 2 questions were absolute a holes

for 12, i was juggingling betwen B and C, and i chose C  mao chose B -.-
for 13 i was juggling between B and C again, and i chose C. lol...

and i screwed up that q to p shit, fk i dont know wtf happened there im sure it was p to q

4 marks is alot, if i got the lenz law explanation right.. do i still get marks regardless of teh directiion i put?

[xers]

fck bro, last 2 questions were absolute a holes

for 12, i was juggingling betwen B and C, and i chose C  mao chose B -.-
for 13 i was juggling between B and C again, and i chose C. lol...

and i screwed up that q to p shit, fk i dont know wtf happened there im sure it was p to q

4 marks is alot, if i got the lenz law explanation right.. do i still get marks regardless of teh directiion i put?

Me too, i was pretty sure it was p to q, and my reasoning was exactly the same as Mao's too, don't know where i went wrong.

[jamestaR`]

Zomg, it was the current through the SQUARE it even had it in bold

[pinchies]

I thought the last one was C, becuase it included the destructive interference resulting in cancellation of sound and therefore apparent distortion. The bit about "different freqs reflect differently" is just saying that theres a lot of freqs hitting the wall and bouncing back to superimpose...

but i could be wrong

C - Without the curtains, different frequencies will reflect differently from the walls, causing distortion due to interference effects.

D - Without the curtains, there would be multiple paths from the speaker to each member of the audience, thus causing distortion and sound loss due to interference effects in some parts of the theatre.

that's the only thing I didn't like about C.
that and, D is more "complete" in saying that there will be distortion as well as sound loss, but only in some parts

anyhow, I could be entirely wrong about different frequencies all reflecting the same...

Fidgey: it does say "smallest wavelength". sorry buddy.

Low frequencies will reverberate off walls, refracting differently, not as sharply as the high frequencies. The curtains will absorb higher frequencies, and will diminish reverb in the hall. This reverb could be considered to be distortion if it occurs as a slap-back echo (particularly with flat walls), and may cause a 'muddying' of the sound.
Reverb must be carefully controlled as not enough will make the sound very 'dry', so this question really needs an expert. I tried talking to my dad, who (many-many years ago, mind you) ran his own sound studio, and even he was not able to decide between them. :-/

[Mao]

^^ that was full of wisdom I cannot comprehend

ahhhhh