Author Topic: ALL PHYSICS DOUBTS - POST HERE !!  (Read 225315 times)

Offline Shazizzzle

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2115 on: May 26, 2010, 06:54:50 pm »
Has to be. It was an MCQ in today's paper 1. I did electric shock..

Anyway, I've got just one question today, like you know when we heat something, after we stop, we take the greatest temperature rise. In question 5 (c), November 2008, why are we subtracting 16.3 from 2.1?? I mean will the heater's heat not melt more ice after the it's switched off?? (If this question has been answered, just tell me the page number)

Secondly, say if we're asked to find the latent heat of vaporisation of water, so we calculate the energy given AFTER it reaches the boil right?? Similar in ice like we calculate the amount of heat given AFTER it melts a little??? And like can a joule meter be used in a circuit like say we're using a heater. As soon as the water starts to boil, you switch on the joule meter. Basically, what I want to know is that will current flow through if it is not switched on???? (So we can switch it on at any time and calculate the energy only for that interval??)

Page 137 for first one.
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Offline rhea

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2116 on: May 26, 2010, 07:02:31 pm »
what are the advantages of using?
a) split ring
b) slip ring


REPLY SOON!!
urgent!!

Offline Vin

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2117 on: May 26, 2010, 07:05:16 pm »
oooh i see i hav missed a lot here .. :P

Any pending ques ?? :P

Good job Aadi, Shazizzzle, Ivo, Kimo, Adzel .. (am i missing someone ?? )

thanks ;) .. for what ?? ..because even I had a couple of small doubts which were solved here

Offline Vin

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2118 on: May 26, 2010, 07:07:09 pm »
what are the advantages of using?
a) split ring
b) slip ring


REPLY SOON!!
urgent!!


ok slip ring is used in AC generators ..
Split ring is used in DC motors and DC generators .. lemme fetch images


A.C. Generators
               


DC Generator



DC Motor

« Last Edit: May 26, 2010, 07:12:38 pm by ~VIN1094~ »

Offline Ivo

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2119 on: May 26, 2010, 07:08:34 pm »
http://www.freeexampapers.us/IGCSE/Physics/CIE/2009%20Nov/0625_w09_qp_31.pdf

Q6)b)ii) Why does it stay the same? Isnt it supposed to be constant?

Thanks :)

This question hasn't been answered yet, and I'm stuck on this as well.  Many thanks in advance.
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Offline Malak

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2120 on: May 26, 2010, 07:09:14 pm »
oooh i see i hav missed a lot here .. :P

Any pending ques ?? :P

Good job Aadi, Shazizzzle, Ivo, Kimo, Adzel .. (am i missing someone ?? )

thanks ;) .. for what ?? ..because even I had a couple of small doubts which were solved here

Hehe yeah a pendin Q  ::)

http://www.freeexampapers.us/IGCSE/Physics/CIE/2009%20Nov/0625_w09_qp_32.pdf

Q9 part c all  ::)
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Offline mdwael

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2121 on: May 26, 2010, 07:14:26 pm »
Can someone please explain me questsion 1 b iv part in oct nov 2006 paper 3 physics? what is cork and how do you find its density ???
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Offline Dana

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2122 on: May 26, 2010, 07:32:55 pm »
Can someone please explain the whole concept of the LDR for me pleasee?? It's quite confusing.

Offline rhea

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2123 on: May 26, 2010, 07:33:19 pm »
ok slip ring is used in AC generators ..
Split ring is used in DC motors and DC generators .. lemme fetch images


A.C. Generators
               


DC Generator



DC Motor



could you explain that in a lil detail..as in the slip rings..

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2124 on: May 26, 2010, 07:34:54 pm »
0625/32/M/J/09  ques 7 b pleazz
i noe de fact dat evaporation is a coollin effect
bt dint gt de othr parts of ms!!!!!!

Offline Helium

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2125 on: May 26, 2010, 07:37:09 pm »
0.05g = 1s
Xg = 20X seconds

120*20x = specific heat of vaporization * X

specific heat ........  = 2400X/X = 2400kJ/kg

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Offline Adzel

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2126 on: May 26, 2010, 07:38:12 pm »
@ rhea:

The function of a slip ring is to make one or more continuous electrical connections from points in a stationary unit to points in a rotating section. Electrical connections on slip rings can be for both power and data signal connections.

Offline Vin

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2127 on: May 26, 2010, 07:39:46 pm »
This question hasn't been answered yet, and I'm stuck on this as well.  Many thanks in advance.

ok this is Charles' Law

The volume of a fixed mass of gas is directly proportional to its temperature if the pressure is kept constant

meaning there is an increase in volume due to the temperature rise    because the pressure is constant  

so here the change in vol. in b)i) is only possible because the pressure is kept constant .. so no change


Offline mdwael

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2128 on: May 26, 2010, 07:44:06 pm »
There is this experiment in oct nov 2006 question 5 (b) how do you carry it out? what do you have to draw, the MS is not clear.. can someone please do it for me?
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Offline Ivo

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2129 on: May 26, 2010, 07:44:49 pm »
ok this is Charles' Law

The volume of a fixed mass of gas is directly proportional to its temperature if the pressure is kept constant

meaning there is an increase in volume due to the temperature rise    because the pressure is constant  

so here the change in vol. in b)i) is only possible because the pressure is kept constant .. so no change



So Boyle's Law is that if temperature is constant, then when volume decreases, pressure increases?
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