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Author Topic: IGCSE PHYSICS DOUBTS HERE !!!!  (Read 54635 times)

Offline The Golden Girl =D

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #60 on: January 16, 2011, 04:30:10 pm »
Quote from: $~SauD~$ on January 16, 2011, 04:21:36 pm
Need Help!
Question 6, part (a)
First variant .... i would be glad if you tell me the procedure...
and if you want the formula it is ----> refractive index= sin i/ sin r :)

the refractive index is given as 1.49 in the part (b) ....and when you go back to the Image the INDEX angle is 30 degree ,and the refractive angle is UNKNOWN...use the formula as follows:

1.49 = sin 30 / sin r

sin r *1.49 = sin 30

r = sin-1 [ sin 30 / 1.49 ]

the sin-1 is done by pressing shift and then sin on the calculator ;)

and you'll get the answer =]
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Offline SauD~

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #61 on: January 16, 2011, 04:32:56 pm »
Thats easy. and i also did that way but the answer is ---> 48.2 >.<
WHY?!?!?! is that :)
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Offline SauD~

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #62 on: January 16, 2011, 04:35:43 pm »
And I would love to share, this with all...
These are notes i found on sf, but were faulty, incomplete and understandably and also added some of mines :D :D :D :D :D.....
Thanks  8)
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Offline The Golden Girl =D

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #63 on: January 16, 2011, 04:39:57 pm »
Quote from: $~SauD~$ on January 16, 2011, 04:32:56 pm
Thats easy. and i also did that way but the answer is ---> 48.2 >.<
WHY?!?!?! is that :)

Maybe your calculator isn't functioning ,remember what ya told me last time ? ....ya so check it ;)
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Offline SauD~

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #64 on: January 16, 2011, 04:45:25 pm »
Answer in mark scheme is 48.2 and the answer i am getting doing that method is 19.6
>.<
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Offline The Golden Girl =D

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #65 on: January 16, 2011, 04:47:33 pm »
thanks for finally sharing Saud :D
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Offline SauD~

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #66 on: January 16, 2011, 04:50:24 pm »
Quote from: ~ The Golden Girl ~ on January 16, 2011, 04:47:33 pm
thanks for finally sharing Saud :D
Welcomez... but first i want answer :D
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Offline The Golden Girl =D

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #67 on: January 16, 2011, 04:57:04 pm »
I can't seem to get the 48.2 to be honest o.0

I'll let someone help u.
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Offline Arthur Bon Zavi

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #68 on: January 17, 2011, 12:29:06 pm »
n = sinr/sini OR n = sini/sinr in any form
sinr/sin30 = 1.49 OR sinr = 1.49 × sin30
48.1°

^ This is from the mark scheme.

The answer should be that found by you, because when it escapes from the prism, it will have a greater speed and therefore the refractive index will be low.
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Offline SauD~

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #69 on: January 17, 2011, 12:49:32 pm »
Quote from: Fidato on January 17, 2011, 12:29:06 pm
n = sinr/sini OR n = sini/sinr in any form
sinr/sin30 = 1.49 OR sinr = 1.49 × sin30
48.1°

^ This is from the mark scheme.

The answer should be that found by you, because when it escapes from the prism, it will have a greater speed and therefore the refractive index will be low.

Can you tell me why are they multiplying, when the formula is n = sin i/ sin r :-|
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Offline Arthur Bon Zavi

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #70 on: January 17, 2011, 12:53:47 pm »
Quote from: SimoN on January 17, 2011, 12:49:32 pm
Can you tell me why are they multiplying, when the formula is n = sin i/ sin r :-|

Because the mark sheet says, that the candidate can take it in any form, but the reason is that which I mentioned above.
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Offline Vin

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #71 on: January 17, 2011, 02:21:21 pm »
Remember this::

From rarer to denser medium.

(AIR  to  GLASS)

n = sin i / sin r

...

From denser to rarer.

(GLASS  to  AIR)

sin r / sin i
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Offline Arthur Bon Zavi

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #72 on: January 17, 2011, 02:22:20 pm »
Quote from: Vin on January 17, 2011, 02:21:21 pm
Remember this::

From rarer to denser medium.

(AIR  to  GLASS)

n = sin i / sin r

...

From denser to rarer.

(GLASS  to  AIR)

sin r / sin i


I was thinking the same.
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Offline SauD~

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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #73 on: January 17, 2011, 02:23:39 pm »
Quote from: Vin on January 17, 2011, 02:21:21 pm
Remember this::

From rarer to denser medium.

(AIR  to  GLASS)

n = sin i / sin r

...

From denser to rarer.

(GLASS  to  AIR)

sin r / sin i

Thanks,
i was thinking but didnt apply :-[
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Re: IGCSE PHYSICS DOUBTS HERE !!!!
« Reply #74 on: January 17, 2011, 02:33:11 pm »
I remember this question.

Yeah, Vin is correct.
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