The Student Room Group

Monday May 14 2012 - CIE Physics Paper 4

So, just thought I'd create this thread for all us CIE students to discuss the exam after we've done it.

Just a note, you'll should not post up answers here to the exam paper until the very next day.

So how's everyone's revision going ? :tongue:
(edited 11 years ago)
Reply 1
Original post by Ari Ben Canaan
So, just thought I'd create this thread for all us CIE students to discuss the exam after we've done it.

Just a note, you'll should not post up answers here to the exam paper until the very next day.

So how's everyone's revision going ? :tongue:


Lol. I will try to avoid discussing it until my exams are over. Anyway, done with physics already, revising chemistry. :holmes:
Original post by Zishi
Lol. I will try to avoid discussing it until my exams are over. Anyway, done with physics already, revising chemistry. :holmes:


Cool stuff. I'm just going through things one last time.

Just got to remain calm and composed now !
Original post by Zishi
Lol. I will try to avoid discussing it until my exams are over. Anyway, done with physics already, revising chemistry. :holmes:


You remember that question in May 2009 Paper 4 ?

Question 9.... Do you understand how they got the answer to the last part ?
Reply 4
Original post by Ari Ben Canaan
You remember that question in May 2009 Paper 4 ?

Question 9.... Do you understand how they got the answer to the last part ?


Yeah, the 0.92 is N/No. No is 0.98 times 3.5x10^2 and N is 0.9 times 3.5x10^5. Do you get it?
Original post by Zishi
Yeah, the 0.92 is N/No. No is 0.98 times 3.5x10^2 and N is 0.9 times 3.5x10^5. Do you get it?


No, unfortunately :/
Reply 6
Original post by Ari Ben Canaan
No, unfortunately :/


It talks about the uncertainty. 2% means that during first time interval the 2% of the nuclei decay and 98% remain. That's why we multiply the initial number of nuclei by 0.98 to get the nuclei we have. And for the maximum uncertainty of 10%,the 10% of original nuclei should have decayed and so at that time we'll have 90% of the initial nuclei. That's how I have done it. Mark scheme changes it directly to 92% for further calculation.
(edited 11 years ago)
Original post by Zishi
It talks about the uncertainty. 2% means that during first time interval the 2% of the nuclei decay and 98% remain. That's why we multiply the initial number of nuclei by 0.98 to get the nuclei we have. And for the maximum uncertainty of 10%,the 10% of original nuclei should have decayed and so at that time we'll have 90% of the initial nuclei. That's how I have done it. Mark scheme changes it directly to 92% for further calculation.


But that's a 2% uncertainty how does it imply a decay of nuclei ?
Reply 8
Original post by Ari Ben Canaan
But that's a 2% uncertainty how does it imply a decay of nuclei ?


It means that there will be an error of 2% while measuring the count rate. So to make allowance for the error, I have assumed that 2% of it decays during the first time interval. Anyway, I don't think that my way is perfect(although it does give the correct answer), so I think you should make a thread about it in physics help forum.
(edited 11 years ago)
Reply 9
Subbed

From what I remember I took the initial as 100, the final as 92, and plugged it in the formula
Original post by Zishi
It means that there will be an error of 2% while measuring the count rate. So to make allowance for the error, I have assumed that 2% of it decays during the first time interval. Anyway, I don't think that my way is perfect(although it does give the correct answer), so I think you should make a thread about it in physics help forum.


Any idea why the amplitude of the information signal has to be less than half the amplitude of the carrier wave ?
Original post by Ari Ben Canaan
Any idea why the amplitude of the information signal has to be less than half the amplitude of the carrier wave ?


As the course book says, "the variation in amplitude at top would be confused with the variation in amplitude at bottom of the wave". Too bad that it doesn't say much more about it. :dontknow:
Original post by Ari Ben Canaan
Any idea why the amplitude of the information signal has to be less than half the amplitude of the carrier wave ?


What variant will you be giving? 41, 42 or 43?
Original post by Zishi
What variant will you be giving? 41, 42 or 43?


42. You ?
Original post by Ari Ben Canaan
42. You ?


Same.
Anyone doing IGCSE?
Original post by YaaahSarah
Anyone doing IGCSE?


This is an A Level thread :P

I did my IGCSEs.
Reply 17
mayn i'm getting 100 fo sho inshallah
Original post by Ari Ben Canaan
This is an A Level thread :P

I did my IGCSEs.


Ohh, sorry! :colondollar: *awkwardly exits*
Reply 19
can we discuss the answers for physcis 42 here?
and does anyone put up the paper with solutions here?

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