Exam 2 - good or bad?

[#1procrastinator]

Bloody disaster for me. I forgot to include a couple of formulas in my notes
and that resulted in me not being able to complete a couple of questions. Think I'd be lucky
to get 50%. That's what you get for trying to cram everything into 7 hours before the exam.
Ah well, can't do anything bout it now.

Third time's a charm, see you next year class of '13, hahahahahahahaha

[InsaneMcFries]

I found it fairly easy, however it was a bit more time consuming than other years. Probably got at least 2 MC wrong and maybe some worded marks. Overall I was pretty happy.

[wanigara]

How did you go with AC motor question?

[InsaneMcFries]

That took a bit of thought, finding the current relied on unit 3 electricity. I just found the voltage drop over the power lines using the resistances, and then divided it by the resistance to find the current. I still found it took a while.

[Mr Keshy]

I promised myself I won't read this thread... It's going to make me worry more than I want to.

Before this thread flies, I found electricity pretty good, light not so good, Detailed, alright.

I'll stop here!

Hope everyone did well!!

[ZanyCat]

For the question about two methods to reduce power loss...

First was obviously use a transformer.

But the second was confusing me. I was initially thinking to decrease the resistance by using thicker wires or a better conductor or electricity, but because I=V/R, if R decreases then I increases! And because PLoss=I^2R, any slight increase in I will be squared and actually increase the power loss by quite a bit.

So I eventually said to 'add more transmission wires in parallel', but that's effectively the same as decreasing R/increasing I, and at that point I gave up.


So which of the answers for the second method is correct (1: decrease R, or 2: add in parallel)? Are none correct, is one correct and the other isn't, or are both correct?

very confuzzled

[vcestudent94]

fuck fuck fuck. I fucked up the whole transmission question, 5 marks definitely gone! I dont know what I was thinking, I went: I=V/R=900/18=50A but i know thats wrong fuck. Then I used that for the next 3 mark question. Please can anyone help me: If I used the wrong current of 50A in determining the Power loss in the next question, would I get ANY consequential marks? Please I need this answered Im dying!

[sh00my]

Moderate exam.
There were many easy marks, but a few difficult marks. I doubt I'll be getting an A+.

My prediction for the cutoff is approximatly 89%.

The path difference question which required you to find the new wavelength will seperate students, and a lot will get caught up in finding the energy of one X-ray photon. Lastly that electron shell question was very difficult, I spoke about standing waves ect but doubt I'll be getting 3/3 for that one.

[afridilegend]

#### - I couldn't finish it!!

Physics was my only hope... Anyone else find it a tad too long?!

what do you think the A+ cut-off score will be?

#@$%!

[sh00my]

fuck fuck fuck. I fucked up the whole transmission question, 5 marks definitely gone! I dont know what I was thinking, I went: I=V/R=900/18=50A but i know thats wrong fuck. Then I used that for the next 3 mark question. Please can anyone help me: If I used the wrong current of 50A in determining the Power loss in the next question, would I get ANY consequential marks? Please I need this answered Im dying!

You will lose one mark max, assuming you showed working for the other questions. Relax you will be fine.

[studynotes]

i forgot to put the line at NE i just put it as east fuck my lifeeeeee
im the only one who got q1 wrong

[#1procrastinator]

I did that too. Sheeeeeeeeeeeeeeeeeeeeeeeeeeeeeit. What was the next one? I just guessed and put the unchanged one

[Fayab25]

So which of the answers for the second method is correct (1: decrease R, or 2: add in parallel)? Are none correct, is one correct and the other isn't, or are both correct?

very confuzzled

For the 2nd method decrease R is correct

[availn]

i forgot to put the line at NE i just put it as east fuck my lifeeeeee
im the only one who got q1 wrong

I'm not actually sure if it's NE, someone said it was SE, because the arrow was pointing at magnetic north. We'll need a copy of the exam to see.

Pretty neat exam, nothing out of the ordinary. Might have lost a mark on that first question, and probably dropped some in those bloody explain questions.

[vcestudent94]

fuck fuck fuck. I fucked up the whole transmission question, 5 marks definitely gone! I dont know what I was thinking, I went: I=V/R=900/18=50A but i know thats wrong fuck. Then I used that for the next 3 mark question. Please can anyone help me: If I used the wrong current of 50A in determining the Power loss in the next question, would I get ANY consequential marks? Please I need this answered Im dying!

You will lose one mark max, assuming you showed working for the other questions. Relax you will be fine.

Thank you for your kind words, however the way I  alculated the current was completely illogical since I just assumed that the motor would get 900V in th first place. I then went on to calculate the power loss which left the motor with less than the required power to use 9000V. Do you get what Im saying? But if I applied the rules correctly:Ploss=I^2R how many method marks am I looking at, 1 out o the total 3?