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AQA physics UNIT 3 monday 30th jan 2012

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yea someone else put that though I put 30. the reason I did was because we had no specific observations other than 10,20,30,40,50 though your probs right! :biggrin:

Reply 41

krishman

think your right - it was 21 - i put 50 :frown:

i so hope the grade boundaries are low !

yeaa man :/

What do you right for the bodes law one?

Reply 44

Unknown505

What do you write for the bodes law question??

Reply 45

GwuanGwuan

for the mirror qu i did in pencil only when i was re drawing it in pen, the invigilator made me rush so i dunno if where my pen lines meet are at at the same place as where my pencil lines are........ :frown:

Reply 46

GwuanGwuan

that it was right as 4/6 where spot on calculations only 2 weren't and 1 was off by 0.1 and another off by 0.5

i put that too!

cool can't be that bad then
hopefully boundaries will b v v v v low of everyone is findin it hard

Reply 49

krishman

i hope so too :smile:

id love it if that happened for biology3 and chemistry3 too

Reply 50

VY Rose

I retook this earlier because I messed it up last time and it bought my overall grade down... so perhaps I'm in a decent position to advise :P !

What did you guys put for the 'step up' question? It said something like 'Minimum amount of coils to make the apparatus a step up transformer'?

After a little thinking I looked at the diagram, counted the coils on the first (14) and put 15 as my answer :P I'm not sure why people here have looked at voltage on the graph. If you have fourteen coils on one, you simply need more on the other to step up!!

As far as the calculations go, I recall....

Magnification was 3.14

30,000Hz
0.15m from front of screw.

960Nm for children.
Boy produced 600Nm.
The boy weighed 375N...

Hope this reassures some people :P Also, roughly 35 raw marks for A*, 30 A, 25B... :smile:

Reply 51

sandeater

Original post by VY Rose

how did you get 0.15m for the front of the screw i spent ages trying to do it but i couldn't explain?>???

Reply 52

sandeater

what did everyone put for how the cameras is different to the ray diagram you had to draw?

Reply 53

Zaii786

Original post by VY Rose

I retook this earlier because I messed it up last time and it bought my overall grade down... so perhaps I'm in a decent position to advise :P !

What did you guys put for the 'step up' question? It said something like 'Minimum amount of coils to make the apparatus a step up transformer'?

After a little thinking I looked at the diagram, counted the coils on the first (14) and put 15 as my answer :P I'm not sure why people here have looked at voltage on the graph. If you have fourteen coils on one, you simply need more on the other to step up!!

As far as the calculations go, I recall....

Magnification was 3.14

30,000Hz
0.15m from front of screw.

960Nm for children
Boy produced 600Nm.
The boy weighed 375N...

Hope this reassures some people :P Also, roughly 35 raw marks for A*, 30 A, 25B... :smile:

Yeh i wrote 15 coils at first, but i dont think the diagram was accurate - you had to work out the number of coils from the graph

Reply 54

Manunited_96

Original post by VY Rose

Noo the number of coils minimum was 21 u had to look on the graph and see how many coils produced a 2v p.d and that was 20 therefor to get a step up transformer 21 was needed, 30,000Hz is also incorrect there was 4 frequency waves so u did 1\0.000001 which gave you 10,000 x 4= 40,000 humans cannot hear this because it's above the audible range of 20,000hz blah blah

Reply 55

VY Rose

Original post by Zaii786

the least number of coils question i put was 21, because the voltage through the first coil was 2V and you had to use the graph to find the number of turns (which was 20, but secondary needs to be more than primary to step current up) so 21! Did anyone else put 21?

Oh dear, seems I was assuming the diagram showed a neutral transformer... oops!

Reply 56

TheMalevolent

That exam was way to hard for a 35 A* boundary, you might scare people :P

A* will be about 31-32 I'm guessing, judging on the amount of people who thought it was hard.

I got 3cm for the screw-crack question and LOL I wrote 960,600 and 375 at first and just confused myself in the end so I wrote something like 240, 150 :L

Reply 57

VY Rose

Original post by Manunited_96

There were only three waveforms within the area marked, I'm certain! The '0.00001m' marking didn't cover the whole oscilloscope :rolleyes:

Reply 58

VY Rose

Original post by TheMalevolent

Fair enough - 35, 30, 25 is rounding up anyway. I wouldn't be surprised if the raw marks went as low as 30 on this.

I wasn't particularly satisfied with the screw question - I used d = v/t where t was five times what the divisions were and v was 6000. Can anyone remember the time base for the oscilloscope? The time each block was worth, that is :smile:

Reply 59

mazam

Original post by VY Rose

I wrote 15 as well though I'm not sure if its right. :frown:

Also how did you get the answer 3.14 for the magnification?

And 0.15m for the screw question, don't you have to divide it by two. As 0.15 is the distance there and back and you want the distance to the crack.