Biology; Chemistry; Physics: Post your doubts here!

[nightmaressana]

heyy is this transistor, astable and bisatable stuff in o levels physics? i know capacitor is but never read this other stuff.... plz tel me its not in our course!! >__<


Also can anyone explain the advanced electronics section of physics o levels course and half life of radioactive substances too.... bcuz we did it in a jiff at school and i don't get it still. help me!!

transistor astable and bistable are in the syllabus but they dont come often, thats what my teachers say.

 

[Duanoor]

can anyone tell me why the smoke goes up in the sky from the chimney in dry day while the smoke goes goes down in wet day.... my friend told me that dry air is heavier than wet air harder for me to believe but can anyone help

nai yr dry air is less dense than wet...thts why smoke goes up in dry air cz dry air exerts less opposing force

 

[mintchocolate4567]

a) Because the fuse will blow at 10 A and the fan will never work. (fuse rating too low)
b) Because the fuse will never blow even if current exceeds 1.5 A. (fuse rating too high)

wont the radio in part b blow up?

 

[Tharindu]

Describe Terminal Velocity

 

[AnGeL.Of.DaRkNeSs]

PHYSICS QUERY :
is it necessary to do past papers before 2000??? seriously i have classfied which has p.p questions of 92 or 94 but the latest pattern and new questions differ from old ones AND i am too lazy to download syllabus can anyone tell me ARE DIODES,TRANSISTORS,CAPACITORS in our syllabus??

 

[smzimran]

wont the radio in part b blow up?

THATS IRRELEVENT. YOU DONT HAVE TO WORRY ABOUT THE RADIO.
BTW, it will blow when current exceeds 1.5 A.

 

[smzimran]

PHYSICS QUERY :
is it necessary to do past papers before 2000??? seriously i have classfied which has p.p questions of 92 or 94 but the latest pattern and new questions differ from old ones AND i am too lazy to download syllabus can anyone tell me ARE DIODES,TRANSISTORS,CAPACITORS in our syllabus??

No, you dont have to.
Questions back then were quite difficult compared to now, and some additional topics were also there that no longer exist in the syllabus.
So, dont waste precious time.

 

[Khalil Rizvi]

No, you dont have to.
Questions back then were quite difficult compared to now, and some additional topics were also there that no longer exist in the syllabus.
So, dont waste precious time.

I guess it won't cause any difference if your concepts are good enough. It doesn't matter whether a question is old or new. It's just the understanding of the question and topic which leads you to the answer. Practice makes a man/(woman ) perfect Rest is on you.

 

[Khalil Rizvi]

Does anyone have June and Nov. '11 Chemistry and Physics Papers(I,II and IV) ?

 

[daredevil]

PHYSICS QUERY :
is it necessary to do past papers before 2000??? seriously i have classfied which has p.p questions of 92 or 94 but the latest pattern and new questions differ from old ones AND i am too lazy to download syllabus can anyone tell me ARE DIODES,TRANSISTORS,CAPACITORS in our syllabus??

diodes (symbols) and semiconductor diode's working are included .... other than that tranistors are not included but capacitors are included in the chapter Advanced Electronics.

 

[daredevil]

interference occurs when two waves fall in the same medium..there are two types of interference :constructive interference and distructive...constructive occurs when crest falls on crest or trough falls on trough...distructive occurs when crest falls on trough.....we can observe interference by young's double slit experiment...

is this intereference included in cie o levels?

 

[snowbrood]

nai yr dry air is less dense than wet...thts why smoke goes up in dry air cz dry air exerts less opposing force

sorry to say but u are wrong wet air is dense than dry air.when water vapour increases the amount of oxygen and nitrogen per unit volume.furthermore as molecule of water is is 18amu while N2 is28 and O2 is 32.. when water vapor increases, the amount of Oxygen and Nitrogen decrease per unit volume and thus density decreases because

 

[Duanoor]

is this intereference included in cie o levels?

no...its not included

 

[Duanoor]

sorry to say but u are wrong wet air is dense than dry air.when water vapour increases the amount of oxygen and nitrogen per unit volume.furthermore as molecule of water is is 18amu while N2 is28 and O2 is 32.. when water vapor increases, the amount of Oxygen and Nitrogen decrease per unit volume and thus density decreases because

well can u pls make me comprehend more clearly...i am unable to understand...

 

[scouserlfc]

sorry to say but u are wrong wet air is dense than dry air.when water vapour increases the amount of oxygen and nitrogen per unit volume.furthermore as molecule of water is is 18amu while N2 is28 and O2 is 32.. when water vapor increases, the amount of Oxygen and Nitrogen decrease per unit volume and thus density decreases because

just explain in terms of the density,like in humid air the mass of water vapour to air is more vapours per the unit volume and thereofre the more denser it is !

 

[scouserlfc]

so guys two months or less than that now,whose still preparing and whose completely prepared and doing Past papers ! And who are the people who havent even touched anything

 

[Birdie Honey]

HEY!!!!!WHY DO WE NEED TWO FIXED POINTS??????AND HOW ARE WE GOING TO EXPLAIN ITS NEED!!!!!!

 

[SalmanPakRocks]

HEY!!!!!WHY DO WE NEED TWO FIXED POINTS??????AND HOW ARE WE GOING TO EXPLAIN ITS NEED!!!!!!

points for what?

 

[Birdie Honey]

points for what?

thermometers!!!

 

[Vogue]

thermometers!!!

yea we need to calibrate a thermometer under two fixed points, i.e. lower fixed point (melting point of ice) and upper fixed point (temp of steam). We do this to mark two extreme positions in a thermometer and then mark all the divisions between those two points. For example in a normal thermometer, there are 100 divisions and each division show a change of 1 degree centigrade. While two fixed positions remain 0 degree centigrade and 100 degrees centigrade.