CONFIRMED mc answers! (2 Viewers)

[colonel73]

hmm think i got bout 12 out of the 15 then guess thats alright =)

 

[since]

I got 14 out of 15, I lost one mark on freaking easiest question -6

 

[Loganrah]

15 is B. We all agree that electrons will move to the left in that instance. Since this is a P-type semiconductor the MAIN conduction (which is what was asked for) will come from electrons filling the holes in the VALENCE band of the boron atoms. The holes are not in the conduction band, they are holes where there is a bond missing.

(Can't believe I got the one about cathode rays wrong :angry: That's probably the only one I got wrong there though )

 

[echeng]

surely its Dnow

 

[mwaug05]

i swear regardless coz its not measuring time its measuring gravitational stuff, that the independant is still time as time is always independant of itself, if it was finding the affect of height changes on time maybe but it was finding the accel of gravity using height and time, i think teach maybe right wid time being indepedant, i just remember reading its always inderpendant as it is uneffected during the exp just measures diff ob if u change dependant

 

[ktxox]

i put 15 b

 

[cahillzy8]

i think that 15 might be D coz the conduction band is the one which allows electrons to flow, like conductivity is determined by the ability of an electron to reach the condunction band from the valence band

omg wats with these D's for 15. boron was introduced, a group III element, which meant there was one less valence electron in the lattice. this created a hole in the valence band, which caused electrons throughout the valence band to fill in the hole. the answer is B

 

[cahillzy8]

i swear regardless coz its not measuring time its measuring gravitational stuff, that the independant is still time as time is always independant of itself, if it was finding the affect of height changes on time maybe but it was finding the accel of gravity using height and time, i think teach maybe right wid time being indepedant, i just remember reading its always inderpendant as it is uneffected during the exp just measures diff ob if u change dependant

nup horribly wrong. the independent variable is always the one that is adjusted to influence another factor. think of it this way.. the time taken to hit the ground DEPENDS on the change in height. height is the independent variable.

 

[Prosper]

I got 13/15. Lost marks on the two calculation questions, doh! (radius one and time one)

 

[Aaron.Judd]

Ms Pooviah still says 15 is D and 5 is C.

 

[2S1D3]

i think that 15 might be D coz the conduction band is the one which allows electrons to flow, like conductivity is determined by the ability of an electron to reach the condunction band from the valence band

wut?

 

[Felix Jones]

oomg 92 posts and still going on about multiple choice....wtf!


what bout rest of exam??
hmm see for the two wires who got the top one as the pure metalt and bottom as alloy??

 

[bob007]

yeh wire x was the chromium and wire y was the alloy

 

[whatever1000]

Yeh BOB is right it's pretty simple the electrons collide with the impuritys in the alloy causing more resistance as it heats up.

 

[jasonml]

Whichever one conducted better was the pure chrodium

 

[kooltrainer]

QUESTION FOR MC QUESTION 7
why does a changing magnetic field occur in the rotor!? .. induction motor has changing magnetic field in the stator magnets not the rotor. .. if theres is changing field in rotor and changing field in stator, these would get mixed up and wont work ... it should be A coz the field in rotor has to be constant so that external fluctuating field could interact with it and make it turn by lenz law...

MC QUESTION 10:
Why should transistor circuits be stepped down ... these both occur in television hence both require step up ..

 

[lorayne]

i thought Q4 was B lol .. cause when we did the experiment it turned out a linear graph ..
how do we know its a curve ??

 

[lorayne]

QUESTION FOR MC QUESTION 7
why does a changing magnetic field occur in the rotor!? .. induction motor has changing magnetic field in the stator magnets not the rotor. .. if theres is changing field in rotor and changing field in stator, these would get mixed up and wont work ... it should be A coz the field in rotor has to be constant so that external fluctuating field could interact with it and make it turn by lenz law...

MC QUESTION 10:
Why should transistor circuits be stepped down ... these both occur in television hence both require step up ..

you see .. induction motors work a bit differently than normal ones .. a rotating magnetic field is set up by 3 radial pairs of electromagnets . and so induce a current in the squirrel cage rotor .. the magnetic feild interact and cause the rotor to rotate..
and for Q10, i think a transister would blow up if it receives the same voltage as the cathode ray tube lol .. u gotta be careful yes they are both in the TV set .. but a cathod ray tube reqires such high voltages that a tiny transistor cannot handle

 

[caso17caso17]

im prety sure 15 is B coz i reckon it would have been D if it was n-type.. i actulay found the multiple choice the hardest of all!!