Author Topic: IGCSE PHYSICS DOUBTS HERE !!!!  (Read 54679 times)

Offline Ghina Ghayad

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #120 on: April 18, 2011, 10:18:33 pm »
(I know that I am replying after a complete age, but I would like to give you a pure and simple explanation including a clumsy explanation) Ask me if you can not comprehend any of the following----)
For any heat capacity question you are required to use the equation
Heat capacity=Amount of heat gained or lost by a material/Temperature change(the final and initial temperature change)
                   =Q/tThis equation should be linked with the specific heat capacity equation which is
Specific heat capacity(c)=            Heat gained or lost by a material(Q)
                                   ---------------------------------------------------------------
                                         mass of the material(m)xTemperature change
For your question in 0625/01/M/J/03 Q17, the answer is A.As to find the highest thermal capacity for the same amount of heat supplied giving that the Q in the equation [Q/t]is constant, thus the temperature change should be the least among the 4 choices.

Incase the Q value was not constant, you should have considered the equation
Specific heat capacity(c)=            Heat gained or lost by a material(Q)
                                   ---------------------------------------------------------------
                                         mass of the material(m)xTemperature change
The highest thermal capacity can be found by choosing the smallest temperature change including the greatest Q value and though with the greatest mass as the equation----Q=cxmxT.
la 2elaha 2ella anta subhanaka eny konto mina aldalemina

Offline ~ Miss Relina ~

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #121 on: April 19, 2011, 10:22:48 am »
need help with thest doubts plz i'm not sure how todraw them:
2003 June  Q 6
2006 oct/nov Q 7(b)
2004 oct/nov Q 8
2008 june Q 7 (a)
2009 june Q 9

Thanks would appreciate any help  :)
~~~Yarab everything turns alright at the end ~~~
    -----------Ameeeeeeeeeeen------------

Offline NotAbod

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #122 on: April 19, 2011, 10:56:57 am »
june 2003
i will solve the others too

Offline NotAbod

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #123 on: April 19, 2011, 11:15:47 am »
october 2006

Offline NotAbod

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #124 on: April 19, 2011, 11:25:53 am »
october 2004

Offline NotAbod

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #125 on: April 19, 2011, 11:33:39 am »
june 2008
srry i did a mistake, the other one was incorrect, download this one
« Last Edit: April 19, 2011, 07:57:19 pm by AboD »

Offline NotAbod

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #126 on: April 19, 2011, 11:50:16 am »
last one
june 2009
 ;D

Kabab

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #127 on: April 19, 2011, 03:56:05 pm »
Damn i am late :P
Abodi good work 8)

Anyways i needed some help too..
Explain me completely about transistor :'(

Offline ~ Miss Relina ~

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #128 on: April 19, 2011, 04:10:52 pm »
june 2008
Thanks a billion billion times words cannot describe ur efforts Thanks again  :D

well could u plz show me the reflection and refraction as in the glass block refraction would ocurr
 and i noticed the in the diffraction graphs u took the the same length of the gap and based on that u u drew the diffracted waves right sorryi really meant thet the the straight part of ur diffracted waves depend on the lenghth of thee gap right?
~~~Yarab everything turns alright at the end ~~~
    -----------Ameeeeeeeeeeen------------

Offline NotAbod

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #129 on: April 19, 2011, 04:22:11 pm »
Thanks a billion billion times words cannot describe ur efforts Thanks again  :D

well could u plz show me the reflection and refraction as in the glass block refraction would ocurr
 and i noticed the in the diffraction graphs u took the the same length of the gap and based on that u u drew the diffracted waves right sorryi really meant thet the the straight part of ur diffracted waves depend on the lenghth of thee gap right?
about the gap, its right, if the gap length is SMALLER than the wavelength, then after passing, the waves will be circular as it is shown in 2004 question, but if the gap length is GREATER than the wavelength, then they would bend the same way i drew them ( straight lines, bend at the ends)

well could u plz show me the reflection and refraction as in the glass block refraction would ocurr
wat do u mean? didnt get u. PM me ur confusion

Thanks a billion billion times words cannot describe ur efforts Thanks again  :D
Your most welcome :)

Demonic, pm me  ;)

Kabab

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #130 on: April 19, 2011, 04:30:23 pm »
A simple Question:
Increasing voltage or increasing current changes the brightness of a lamp?
Like a 230W lamp is used so
A current supply of 5A and 46V will be brighter or supply of 2A and 115V

:D
Thanks

Offline NotAbod

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #131 on: April 19, 2011, 04:44:11 pm »
both current and voltage contributes to the brightness of the lamp.
Brightness is affected by power.
power = Voltage x current
the bulb needs 230W to work at full energy.
5x46 = 230W
2x115= 230W
in both cases, the power supplied is 230
so the brightness will be the same for both
:)
Transistor in few mins ;)

Kabab

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #132 on: April 19, 2011, 04:54:20 pm »
both current and voltage contributes to the brightness of the lamp.
Brightness is affected by power.
power = Voltage x current
the bulb needs 230W to work at full energy.
5x46 = 230W
2x115= 230W
in both cases, the power supplied is 230
so the brightness will be the same for both
:)
Transistor in few mins ;)
what if 2 lamps are place in parallel to each other and battery as well. SO will the lamp glow at full brightness or half brightness.

Offline NotAbod

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #133 on: April 19, 2011, 05:07:17 pm »
what if 2 lamps are place in parallel to each other and battery as well. SO will the lamp glow at full brightness or half brightness.
well, full brightness, both of them
in parallel circuits, they will all get the same voltage, so if the battery is labelled 3V, and the lamp need 3V to work, then both will work at full brightness, because they are getting the same voltage (3V) , whereas if u connect the samp circuit in series, each lamp woud get 1,5V (if they are similar) and they both would glow at half brightness.  ;D

Kabab

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #134 on: April 19, 2011, 05:12:23 pm »
well, full brightness, both of them
in parallel circuits, they will all get the same voltage, so if the battery is labelled 3V, and the lamp need 3V to work, then both will work at full brightness, because they are getting the same voltage (3V) , whereas if u connect the samp circuit in series, each lamp woud get 1,5V (if they are similar) and they both would glow at half brightness.  ;D
Doesn't this prove that voltage changes the brightness of lamp ::)