Physics: Post your doubts here!

[forever_chocoholic]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w07_qp_4.pdf
Qn no. 5(b)ii.. Could someone please explain why 1cm^2 represents 156 microC?

i am doing as level but i always find it useful to check the 'er', the examiners sometimes explain the questions.. do have a look
http://papers.xtremepapers.com/CIE/...A and AS Level/Physics (9702)/9702_w07_er.pdf

 

[forever_chocoholic]

could someone tell me whats a traveling microscope ? and where do we use it? since they keep mentioning about it in physics paper 3 (in improvements)in mark schemes

 

[A star]

any one some difficult questions pls. P4 :3

 

[JAVERIA INAM DANISH]

How to calculate ratio of alpha:beta?

 

[scouserlfc]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w07_qp_4.pdf
Qn no. 5(b)ii.. Could someone please explain why 1cm^2 represents 156 microC?

Just measure the area of the 1x1 square that u can form it comes out to be
1.25*0.125=0.15625mC = 156.25microC =156microC

This is just the area of one such box so multiply it with the no. of 1 x 1 squares below line to get answer !

 

[salvatore]

Just measure the area of the 1x1 square that u can form it comes out to be
1.25*0.125=0.15625mC = 156.25microC =156microC

This is just the area of one such box so multiply it with the no. of 1 x 1 squares below line to get answer !

How did you get 1.25 and 0.125? Sorry for bothering :/

 

[Namehere]

Anyone can explain Q9 (all) please?

 

[hope4thebest]

any one some difficult questions pls. P4 :3

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_s11_qp_41.pdf Q 5(c) (i)

 

[scouserlfc]

How did you get 1.25 and 0.125? Sorry for bothering :/

You really need the paper in its exact form and dimensions so that u can see the number of small blocks that are present in 1 cm so i actually enlarged the paper to the size we normally have and then used a scale to see what 1cm is. Dont worry in exam this will be easy.

 

[scouserlfc]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s11_qp_41.pdf Q 5(c) (i)

Its clockwise or bottom to top . As u know from part b that magnetic field direction is out of page use this and the Flemings Left Hand rule.

 

[Yousif Mukkhtar]

oh can u tell me which year is it from?

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_s13_qp_43.pdf
May June 13 Q 7c) Paper 43

 

[Yousif Mukkhtar]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w13_qp_43.pdf
Can some one explain Q 7c)

 

[Malik777]

I'm assuming that you got the answers for the previous two parts.. for part (iii),
Intensity received back= (intensity reflected at the muscle-bone boundary)e^-(23 * 4.1 * 10^-2)

[ e^-(23 * 4.1 * 10^-2) = 0.39]


intensity of the wave incident on the boundary was 0.39I, as calculated in part (ii)
0.33 of this was reflected at the boundary.
So intensity reflected at the muscle-bone boundary= .39 * .33I

answer= .39 * .33I * .39 = .050I

I hope this helps

why you multiplied 0.39 twice ? :O

 

[forever_chocoholic]

anyone doing paper 3? i want to as if its fine to use crosses when plotting ur graph?

 

[hela]

Please help
Paper 4 m/j 09 Q11 b) (iii)
http://papers.xtremepapers.com/CIE/...and AS Level/Physics (9702)/9702_s09_qp_4.pdf


Answer
http://papers.xtremepapers.com/CIE/...and AS Level/Physics (9702)/9702_s09_ms_4.pdf

 

[hope4thebest]

Why emf induced in the secondary coil not in phase with emf in the primary coil?

 

[hela]

Please help
Paper 4 m/j 09 Q11 b) (iii)
http://papers.xtremepapers.com/CIE/...and AS Level/Physics (9702)/9702_s09_qp_4.pdf


Answer
http://papers.xtremepapers.com/CIE/...and AS Level/Physics (9702)/9702_s09_ms_4.pdf

hela, 5 minutes agoEditDeleteReport
#9359Reply

 

[sma786]

Hey..
Does anybody want to practise paper 4 papers with me?
If yes please inbox.. I'll tell you my bbm or kik or whatevrr

 

[sma786]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w12_qp_41.pdf

Question 1 part b please..

 

[Monojit Saha]

Please help
Paper 4 m/j 09 Q11 b) (iii)
http://papers.xtremepapers.com/CIE/...and AS Level/Physics (9702)/9702_s09_qp_4.pdf


Answer
http://papers.xtremepapers.com/CIE/...and AS Level/Physics (9702)/9702_s09_ms_4.pdf

hela, 5 minutes agoEditDeleteReport
#9359Reply

Thing is, the ray is being absorbed twice and is being total internally reflected once.
So first I is being absorbed so we have 0.39I being transmitted to the bone and muscle boundary. 0.33 times 0.39 is then being internally reflected so we have 0.33 x 0.39I. Then again when it is moving from the boundary to the outside, it is again being absrbed so we have 0.39 x 0.33x 0.39 I which is why they squared the 0.39.