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pp1 phys , doubt !

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irlzs95

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hey guyz :)
i would be thankful if someone helped me in this question :)
http://www.xtremepapers.me/CIE/Cambridg ... _qp_12.pdf :)
q no 29 , i chose B , but turned out to be c ?? for some reasons !
isnt its wen resistance descrease, voltage decrease , so then the voltage of the other one increases ???
:S

nd for the last question i got it by just guessing , is there specific way in solving it ??
thaanks in advance :)
 
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Ahmooosh

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Okay , for question 29 , u should understand this concept , in potential dividers if one resistor has MORE RESISTANCE , then other one will have LESS RESISTANCE , u can say they are inversely propotional .... And same thing with Voltage , more resistance = More voltage
for last question , yea i cant understand it either ,so please if you get it or someone else please help.
 
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Rahma Magdy

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The Last Question is just to confuse you..
So, here it is.. When You want to get the half life of a substance we divide it by 2 . Right?
- Here, we want how was it in its last half life.. Means before this decay.. which will mean multiplying it by 2 ..Right?
so it's D ..
..
I am not a very good teacher :S
I just hope I helped you :)
 
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irlzs95

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thank u both very much :Rose:

but i hav more 3 Qs , :oops:

http://www.xtremepapers.me/CIE/Cambridg ... 6_qp_1.pdf
Q 16 , i dnt get it at all !! the ans is C

also http://www.xtremepapers.me/CIE/Cambridg ... 5_qp_1.pdf
Q15 isnt it supposed to be high thermal capacity cuz it lost none of heat ?? btw answer is B

http://www.xtremepapers.me/CIE/Cambridg ... _qp_12.pdf
Q16 , why is it D ???


finally , guyz could anyone tell me bout these things bot nuclear nd hydrelectric energy with steam or not .... etc these things , my teacher nvr mentioned them nd i saw them several times in the pp =/


thaaank u alot :) nd srry for asking alot :oops:
 
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Ahmooosh

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hmm question 16 from first link , NOOOO idea... would like to know why aswell ,

Q15 second one , since the operator feels NOTHING that tells you that the object wasnt hot , but they said the spark was very hot , this indicates that the thermal capacity is low , since thermal capacity is how much energy is needed to change 1kg by 1 degrees celcius.

Q16 last one , well convection current , hot air rises , cold air falls .... so the the smoke given of from the candle leaves from the top , then it falls back from the other chimney direction D. my concept to this one isnt really clear so if someone else can explain it to u.

hope i helped ya
 
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Ahmooosh

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Diode is a device that allows current to pass one direction only , it changes A.C to D.C which is known as rectification.

Transistor is a kind of switch , there is base , collecter and emmiter , if the voltage flowing through it is high enough , it conducts electricity and switches on the circuit, used in potential dividers.

Capacitor is a device used to store charges , they have 2 parrallel plates , when you connect them to a battery, the electrons flow from one plate to the battery , leaving that plate positively charged , and the electrons flow from the battery to the other plate making it get excessive electrons , becoming negatively charged.

hope i helped.
 
haochen

haochen

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in question 16 (first link) u need to cncentrate in the question
"A thermometer with no scale is taped to a ruler as shown. When placed in steam, the mercury
level rises to 22 cm. When placed in pure melting ice, the mercury level falls to 2 cm."
so it indicate that 22'C=100'C and 2'C=0'C so there are 10 gaps between them
so 100/10 = 10 so each gap increases the temp by 10'C so start from 2 and reaches to 8 so 3 gaps
so 3 * 10 =30
(u must note it down on the termometer to understand clearly :) )

in question 15 (second link)
it has nothing to do with conductor so C and D is out. and it is low thermal capacity because
it gain heat and loss the heat quickly so the operator feels nothing :)

in question 16 (third link)
when smoke rise , it go out from the chimney above th candle (ofcourse),
the air need to get to the candle so it can burn. that is why air is going down from other chimney,
mean while the smoke is present so it can be seen so it move down the chimney. (if the smoke is not present it will also happen but not seen)

hope u understood :D
i know the explanation of the first is llong :)
 
haochen

haochen

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@Ahmooosh
u need to cncentrate in the question
"A thermometer with no scale is taped to a ruler as shown. When placed in steam, the mercury
level rises to 22 cm. When placed in pure melting ice, the mercury level falls to 2 cm."
so it indicate that 22'C=100'C and 2'C=0'C so there are 10 gaps between them
so 100/10 = 10 so each gap increases the temp by 10'C so start from 2 and reaches to 8 so 3 gaps
so 3 * 10 =30


@irlzs95
in question 9
it is hydroelectric because it use water too produce electricity without producing heat
while nuclear produce heat and elctricity and coal while burning produces heat so only hydroelectric produces electricity by the waves of water :)

hope u got it :D
 
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Ahmooosh

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yea thanks , i did understand , i divided 100/20.... for some reason

whats the average score that people get in past papers paper 1? when practicing at home not in exam.
 
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