# Cambridge Chat (previously New Cambridge Students Entry 2004)

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15 years ago
#11001
(Original post by Willa)
well you have to use (e^jd + e^-jd)/2 = cos d and so on!
By any chance have you done any of the qus from J9 to J11? i'm so stuck!
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15 years ago
#11002
sorry mate, i'm no maths expert, i'm gonna start doing them in about 5 mins, by which time someone will have given you the answer or something
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15 years ago
#11003
(Original post by devilschild)
That is so harsh you really should refuse to pay! Im v glad we dont get fined at our college for setting fire alarms off (as long as not on purpose obviously) just a bit of a telling off. Poor you!
im glad im not the only person who thinks its a bit harsh

but what can you do eh..
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15 years ago
#11004
ellie... i still havent managed to spot you in lectures! youre doing E&B and... cells? right?
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15 years ago
#11005
(Original post by devilschild)
By any chance have you done any of the qus from J9 to J11? i'm so stuck!
i suggest you explore J9 by multiplying z1 and z2 and z1z2* by a complex number with mod:1 and arg:t
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15 years ago
#11006
(Original post by Willa)
i suggest you explore J9 by multiplying z1 and z2 and z1z2* by a complex number with mod:1 and arg:t
Are these the ones with logs of complex numbers and things? I think I remember the sheets from last year.

Ben
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15 years ago
#11007
(Original post by Ben.S.)
Are these the ones with logs of complex numbers and things? I think I remember the sheets from last year.

Ben
Sorry - those questions are in I.
J9: Show that z1z¤2 is invariant under a rotation of z1 and z2 about the origin in the Argand diagram.

Ergh.

Ben
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15 years ago
#11008
anyone want to contribute anything i can say in my prsentation?

2. Presentation - “The importance of molecular organisation in the photosynthetic electron transfer chain”.
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15 years ago
#11009
(Original post by crana9)
ellie... i still havent managed to spot you in lectures! youre doing E&B and... cells? right?
Yep i'm in cells and E&B- i've been trying to spot u as well but haven't seen u! maybe i should go to lectures armed with a foto of you and start looking! in E&B usually am one or two rows from back to left(cos am usually late and thats the only place with space) and cells in the middle towards back sumwhere. is very strange we havent run into each other yet xxx
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15 years ago
#11010
(Original post by crana9)
anyone want to contribute anything i can say in my prsentation?

2. Presentation - “The importance of molecular organisation in the photosynthetic electron transfer chain”.
The precise organisation and orientation of the components of antenna complexes are important for allowing efficient RET to the reaction centres. I'll have to do all this again in tedious detail in Lent. I can't remeber the exact order of the plastoquinone/cyanin rubbish (and can't be bothered to look on my shelf!).

Ben
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15 years ago
#11011
ah ellie.. i normally sit right in front of the projector thingy in E&B, i think i need stromnger glasses, if i sit near the back I cant see the slides properly!! in cells I normally sit in the middle bit at the front near the back of that section hehehe

thanks ben.. it would help if i understood ANY photosynthesis

by the way.. anyone... Is there anywhere in cambridge that sells sewing type stuff? I need a hook and eye and some black thread in an experiment to try and make my gown wearable...Like any big dept,. stores should sell that kind of thing, but i dont recall seeing any?!
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15 years ago
#11012
(Original post by crana9)
ah ellie.. i normally sit right in front of the projector thingy in E&B, i think i need stromnger glasses, if i sit near the back I cant see the slides properly!! in cells I normally sit in the middle bit at the front near the back of that section hehehe

thanks ben.. it would help if i understood ANY photosynthesis

by the way.. anyone... Is there anywhere in cambridge that sells sewing type stuff? I need a hook and eye and some black thread in an experiment to try and make my gown wearable...Like any big dept,. stores should sell that kind of thing, but i dont recall seeing any?!
Robert Sayle has stuff like that - it's up near the Grafton.

There's a fabric shop on Hobson Street which may do some as well.
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15 years ago
#11013
(Original post by crana9)
ah ellie.. i normally sit right in front of the projector thingy in E&B, i think i need stromnger glasses, if i sit near the back I cant see the slides properly!! in cells I normally sit in the middle bit at the front near the back of that section hehehe

thanks ben.. it would help if i understood ANY photosynthesis

by the way.. anyone... Is there anywhere in cambridge that sells sewing type stuff? I need a hook and eye and some black thread in an experiment to try and make my gown wearable...Like any big dept,. stores should sell that kind of thing, but i dont recall seeing any?!
Have you tried the material stall in the market- that sells sewing type stuff as well i think.
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15 years ago
#11014
devilchild....if you havent managed J9 by now, here's the answer I just worked out:

a rotation by angle t is multiplication by a complex number: p = cos t + isin t (since arg(p) = t)....therefore

z1 rotated = z1p
z2 rotated = z2p

taking these new values for z1 and z2, then (New z1)(New z2)* = (z1p)(z2p)* = z1z2*pp*

but |pp*| = 1 (obviously) and arg(pp*) = 0, therefore z1z2*pp* = z1z2*, so is invariant!
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15 years ago
#11015
J10 is easily shown just by expanding it out in terms of real and imaginary parts (use a substitution of a = x + iy and b = u + vi if you wish!)
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15 years ago
#11016
cunning plans nicky & ellie, thank you. i will report back if this is a success.
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15 years ago
#11017
(Original post by Willa)
J10 is easily shown just by expanding it out in terms of real and imaginary parts (use a substitution of a = x + iy and b = u + vi if you wish!)
Thanks a lot for the help, had kinda given up on these 2! do you know what the result of J10 shows geometrically?
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15 years ago
#11018
well i havent got it totally figured out, but basically you want to draw the parallelogram, and you need to show that the sum of the squares of the non-parallel sides is twice the sum of the squares of the diagonals.....but that seems boring so i might try that later.
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15 years ago
#11019
(Original post by crana9)
yup

althought it wasnt exactly frm drinking too much coffee
Goood ol' Pro Plus
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15 years ago
#11020
right....who the hell gave me negative rep for the last post i made.....whoever did that better have a good excuse, otherwise they are the most pathetic person ever!

someone positive rep me, i dont like that red gem
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