A2 Physics | Post your doubts here

[ousamah112]

The ultrasound image
clearly shows the baby's skin and some bones.
Explain why these show up clearly while softer
organs inside its body do not.

those soft organs absorb all or the ultrasound is completely transmitted without any reflection. For any image to be formed there must be some reflection at the boundary of that organ.

 

[mybch]

June 2002 question 6 (a)
diagram please

 

[hassam]

helpful
Two consecutive peaks in an ultrasound A-scan
are separated by a time interval of 0.034 ms.
Calculate the distance between the two
reflecting surfaces. (Assume that the speed of
sound in the tissue between the two surfaces
is 1540ms-I.)
Explain why ultrasound cannot readily be used
to examine the brain. Suggest an alterrıative
scanning techniquels) that can be used for this
i have a very strong feeling that such a question will cum this tym

 

[RGBM211]

which book is it from^

 

[farrukh]

Suggest and explain why there is not a continuous bombardment of old satellites colliding with Earth

 

[hassam]

Suggest and explain why there is not a continuous bombardment of old satellites colliding with Earth

well it will burn up in the atmosphere due to great friction at such high speeds......i remeber this from last year when one of satellite was on verge of colliding bt waas torn to pieces due to huge air resistanceee

 

[hassam]

which book is it from^

chadha's book

 

[hassam]

well i have some doubts in communication chapter.........what has bandwidth to do with quality cos i always thought it has to do with the transmission capacity....if u have got high bandwidth u cn transmit more information.....bt books and ms says fm has greater bandwidth so greater quality........................
secondly one ms says for sky waves that poor reception in hilly areas......while question said why we made a switch from ionospheric reflection to space waves using satellites......now the doubt in my mind is that tthe space waves are of even shorter wavelengths so they are essentially line os sight,,,,isnt it

 

[ousamah112]

help me with may/june 09 p4 q6 part c..

 

[Abdullah syed]

http://www.xtremepapers.com/papers/...and AS Level/Physics (9702)/9702_s04_qp_4.pdf​

Can Any One Help Me Q 1b and 2b(ii)​

 

[ousamah112]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s04_qp_4.pdf​

Can Any One Help Me Q 1b and 2b(ii)​

rms speed at T= 300 is 500
to change rms speed into <c^2> square the rms speed
so twice rms means = 4<c^2>
we knw that <c^2> is directly proportional to T
so T1/T2= <c^2>/4<c^2>
put the values and you will get the answer.

 

[user]

Assalamoalaikum wr wb!

need help with Q:10 a 9702_s07_qp_4.pdf

Is this correct?

​

 

[hassam]

Assalamoalaikum wr wb!

need help with Q:10 a 9702_s07_qp_4.pdf

Is this correct?

View attachment 9106​

no thats faulty...brother.........see the question say 0010 at START so u shud have started from 2 at 0 ms

 

[ousamah112]

Assalamoalaikum wr wb!

need help with Q:10 a 9702_s07_qp_4.pdf

Is this correct?

View attachment 9106​

no its like this. i did in yellow.

 

[hassam]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s04_qp_4.pdf​

Can Any One Help Me Q 1b and 2b(ii)​

please tell how to show anser for 1st question part b

 

[user]

no thats faulty...brother.........see the question say 0010 at START so u shud have started from 2 at 0 ms

no its like this. i did in yellow. View attachment 9109

JazakAllah khairen...!

 

[ninjas4life]

please tell how to show anser for 1st question part b

For Q1 the primary charge is 1.6x10^-19 becase all the values are integral multiples of 1.6x10^-19
for Q2 b (ii) you have to substitute density=Nm/V into the equation given and get the value of <c^2>. do square root to get r.m.s. value.
the answer should be 500.

 

[mybch]

please answer my question as well

 

[Zishi]

no its like this. i did in yellow. View attachment 9109

JazakAllah khairen...!

The question asks to show the final analogue signal. Because you people are showing the digital signal, so that's wrong. Convert the binary numbers to decimal numbers and join the points by making a curve.

 

[user]

The question asks to show the final analogue signal. Because you people are showing the digital signal, so that's wrong. Convert the binary numbers to decimal numbers and join the points by making a curve.

Nopes...that's correct...check the application booklet

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