Physics: Post your doubts here!

[NinjaInPyjamas]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w10_qp_22.pdf

explain no 6?
like in (a) what is the theory behind why we need to divide 1600 ohms?

 

[papajohn]

can anyone do this question for me ?
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s09_qp_2.pdf
Q 5

1a) Path difference (S2M-S1M) b/w the waves from Si amd S2 is an odd number ( 1 3 5...) multiple of half wavelenght
2) Same amplitude at M

The part b is indeed the most difficult question in the history of CIE
B) Distance S2M =128 (from Pythagoras thereom)
Path difference S2M - S1M
128-100 = 28 (If you do not know this concept then take help from Pacific Physics Vol 2 )

Wavelenght at 1 Khz of sound wave is λ=v/f 330/1^103= 33cm
λ of 4kHz 330/4^103= 8.25 cm

Path difference for minima = odd number of the half the λ
Or simply (2n+1) * λ/2
Put n = 0 in the formula (2*0 +1) λ/2 = 56
Put N= 1 =2(1)+1) * λ/2 =18.7
Put N = 2 2(2) =1) * λ/2 = 11.2
Put N= 4 2(3) +1* λ/2 = 8
Sice λ 56 cm and 8 cm are not within the range of 8.25 to 33 cm, so minima is obtained for λ 11.2 and 18.7cm Therefore two minma are detected.
Please pray for As for me in CIE if i helped you..

 

[Mashal zeb]

Plzzz somebody help me out wd da last part

 

[princeali97]

there is this question which i've seen many times in past papers: describe and explain how diffraction and interference is observed in i) ripple tank ii)microwaves/light.You may use a diagram to explain.
I dont understand what exactly should we include in the diagram.Sum1 pls help me in dis !

 

[princeali97]

Plzzz somebody help me out wd da last part

how much is the strain energy in part a)ii) ?

 

[daredevil]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w10_qp_42.pdf

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w10_ms_42.pdf


Q 5 c (ii)

I just don't get it -_-

 

[Snowysangel]

Could someone please answer these!

 

[princeali97]

View attachment 40229
I don't understand part c

bro u must post the circuit diagram too!

 

[princeali97]

plz post the diagram too

bro can u help me with the question i posted above pls :/

 

[Faaiz Haque]

Why doesn't anyone answerrrrr

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_s10_qp_21.pdf

Q2 - B ii
Q4 - B (Explain your calculations please)
Q4 - C

please

 

[salvatore]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w02_qp_4.pdf
Please help me with qn no. 6b(i).
When I try using Fleming's Left Hand Rule, I get the answer as into the plane of the paper (using the direction of the current opposite to the direction of the proton).

I'll be grateful for any explanation given. thanks

 

[sadiaali]

Please someone explain me Q6 of part b with the diagram. Please help
http://papers.xtremepapers.com/CIE/...and AS Level/Physics (9702)/9702_s04_qp_2.pdf

 

[ZaqZainab]

Please someone explain me Q6 of part b with the diagram. Please help
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s04_qp_2.pdf

 

[princeali97]

Please someone explain me Q6 of part b with the diagram. Please help
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s04_qp_2.pdf

Sadia Ali,nothing to worry in this question.Constructive interference occurs when crests of both waves meet.So you just draw a straight line wherever u see the overlapping of the two waves at a point.For destructive interference draw a straight line which exactly is halfway between the first order and the line OX or u can draw a straight line which passes through a crest of one wave and trough of another.Sorry but i can't upload the attachment.I did what i could :/

 

[princeali97]

Can anyone explain why pressure at the top of a mountain is lower than pressure at sea level?..

 

[ZaqZainab]

Can anyone explain why pressure at the top of a mountain is lower than pressure at sea level?..

air has weight
as you move upwards there are less air particles ABOVE YOU being pulled by gravity
Also, on a mountain top, you are away from the center of earths gravity so the air weighs less at that height.

 

[princeali97]

air has weight
as you move upwards there are less air particles ABOVE YOU being pulled by gravity
Also, on a mountain top, you are away from the center of earths gravity so the air weighs less at that height.

Why cant we answer this question on the basis of temperature?Temperature at the top of a mountain is lower than temp. at sea level.So molecules will more kinetic energy at sea level and will apply greater force hence greater pressure.:/

 

[ZaqZainab]

Why cant we answer this question on the basis of temperature?Temperature at the top of a mountain is lower than temp. at sea level.So molecules will more kinetic energy at sea level and will apply greater force hence greater pressure.:/

Then the question arises why is it cold at higher altitude? It goes this way its cold because there is less pressure
the pressure is not less because of the temperature being low
the cause for temperature being low at high altitude is pressure
and the cause of low pressure is the weight of air.....

 

[princeali97]

Ahhh!.....im confused.As far as i know temperature does affect the pressure because as temperature increases the vibration and movement of molecules increases and so the frequency of collisions and the force they exert increases.

 

[ZaqZainab]

I don't think that temperature affects the pressure of air in anyways. And moreover kinetic energy also has no direct relation with pressure.

it does more the temperature more the pressure
what is pressure?continuous physical force exerted on or against an object by something in contact with it.
when you increase Kinetic energy more molecules start exerting force on the walls of a container hence higher pressure