Author Topic: ALL PHYSICS DOUBTS - POST HERE !!  (Read 230218 times)

holtadit

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ALL PHYSICS DOUBTS - POST HERE !!
« on: April 01, 2010, 10:43:14 am »
Okay people !! Post your IGCSE PHYSICS doubts here so there is one central place for all your queries.

I go first :D


Why does increasing the space between the pins in a light ray experiment improve accuracy ? Put it another way : why should there be such a large gap between each individual pin ?


Amr Fouad

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #1 on: April 01, 2010, 10:52:24 am »
well that's simple...put ur two index fingers behind each other and try to spot smth infront of u..it's gonna be hard to spot accurately..

now try widening out the space..c the diff?

in other words..to avoid parallex error..

hope that helped.. :)

holtadit

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #2 on: April 01, 2010, 11:05:12 am »
well that's simple...put ur two index fingers behind each other and try to spot smth infront of u..it's gonna be hard to spot accurately..

now try widening out the space..c the diff?

in other words..to avoid parallex error..

hope that helped.. :)

Thanks Amr. Nice analogy !

holtadit

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #3 on: April 01, 2010, 11:07:59 am »
When calculating the gradient of a line in PAPER 6 a mark is given for drawing a triangle 'more than half the length of the line'.

The examiners report also  refers to the TRIANGLE METHOD alot. What is this method/how does it work.

The only way I know to calc. a gradient is using (y2-y1)/(x2-x1). 

Amr Fouad

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #4 on: April 01, 2010, 11:11:16 am »
well that's exactly the same..

wut the examiners do is that they use a large triangle (to increase accuracy in taking the averag).. and divide the y-side by the x-side..

so wut u should do is draw the trinagle, divide the vertical length by the horizontal one..

hope that helped again ;D

holtadit

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #5 on: April 01, 2010, 11:41:07 am »
Question 3 (b) iii)

Whats a coherent answer ? The MS says increases the k.e. of the water (ignore heat/sound)




During Boiling of water why doesnt the temperature of the liqiuid rise ?
« Last Edit: April 01, 2010, 11:51:37 am by Ari Ben Canaan »

Offline Adzel

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #6 on: April 01, 2010, 12:13:52 pm »
The accurate answer is; that the energy is used to break the bonds.  :)

Offline @d!_†oX!©

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #7 on: April 01, 2010, 04:16:12 pm »
Question 3 (b) iii)

Whats a coherent answer ? The MS says increases the k.e. of the water (ignore heat/sound)




During Boiling of water why doesnt the temperature of the liqiuid rise ?

The answer refers to the concept of "latent heat of vaporization", so just read that part in your textbook to get the exact answer
AAL IZZ WELL!!! ;)

Offline °o.O-hash94-O.o°

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #8 on: April 01, 2010, 05:38:23 pm »
ok everyone use this thread for doubts related to physics ... and dont make multiple threads for physics doubts!

I am making this thread sticky!

holtadit

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #9 on: April 02, 2010, 08:50:37 am »
The answer refers to the concept of "latent heat of vaporization", so just read that part in your textbook to get the exact answer

It just so happens that I have a very sucky, yet expensive, textbook. :P

Stilll wanna help me ?

holtadit

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #10 on: April 03, 2010, 07:40:49 am »
I have a poor understanding of Lenz's law as its not in my textbook and probably not part of my syllabus. But I still want to understand it.

In the attached picture, would the induced e.m.f. flow in direction shown by the RED arrow if the magnet were pushed in the direction shown?



If the magnet were pulled out of the coil would the induced e.m.f. flow in the direction shown by the PINK arrow ?



ALSO in which direction does the pointer kick towards in each case and why ?

holtadit

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #11 on: April 03, 2010, 08:25:00 am »
PLEASE SEE THE ABOVE QUESTION




ONe more too:  if a fuse is rated at 5A does that mean it will blow when the current is AT 5 A or when it EXCEEDS 5A ???

Offline astarmathsandphysics

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #12 on: April 03, 2010, 08:56:24 am »
When it exceeds. It also has to exceed 5A for a short time so the fuse will melt

holtadit

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #13 on: April 03, 2010, 09:08:04 am »
I have a poor understanding of Lenz's law as its not in my textbook and probably not part of my syllabus. But I still want to understand it.

In the attached picture, would the induced e.m.f. flow in direction shown by the RED arrow if the magnet were pushed in the direction shown?



If the magnet were pulled out of the coil would the induced e.m.f. flow in the direction shown by the PINK arrow ?



ALSO in which direction does the pointer kick towards in each case and why ?



Please this question too astar.

Offline The Golden Girl =D

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Re: ALL PHYSICS DOUBTS - POST HERE !!
« Reply #14 on: April 03, 2010, 02:22:12 pm »
no in the pink arrow's direction
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