Physics: Post your doubts here!

[OmarKamal]

Can u guys help me in J13/21 Question 5 part c. How do we know if there's 5 maxima and 6 minima between O and P?

 

[AhsanAfzal]

no. when in parallel to LDR the p.d = 20
when in series with ldr the p.d <20 as p.d of both LDR+R2 = 20

why LDR + R2? they are asking about minimum pd across only R2
and there is no LDR in series one -.-

 

[Asad Moosvi]

Is anyone worried about physics?

 

[sma786]

http://papers.xtremepapers.com/CIE/...S%20Level/Physics%20(9702)/9702_w10_qp_21.pdf

Question 2(a).. Why do we take tan for vertical component? Why not sin?
Explain please..
Markscheme: ( http://papers.xtremepapers.com/CIE/...S%20Level/Physics%20(9702)/9702_w10_ms_21.pdf )

 

[Manobilly]

Is anyone worried about physics?

A2?

 

[Zepudee]

it was 5 ms which is =1/4T
it was initially at the 1/4th from my diagram so add 1/4 we get 2/4th stage.

Aw Suchal riaz, I still cannot understand Can you please explain more in detail? BOOHOO I have been stuck in this question for a very long time.

 

[Zepudee]

i think you need some pictures to help you learn it.
View attachment 42439
does that make anything clear?

OHH I DO NOW HAHAHAA THANKS!!

 

[Snow Angel]

Hope all thing is Visible
View attachment 42368

Thnx
please can u explain the q 4b iv) 3. from: papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w11_qp_23.pdf

why do they add the values to find the p.d across cell B?
and q 4biii) from: papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w12_qp_21.pdf

Please reply as soon as possible. Thnx in advance.

 

[Snowysangel]

What's the formula of uncertainty? Is it uncertainty in x/value if x= 1/2(uncertainty in y/value of y + uncertainty in z/value of z)? Or do we remove the half?

 

[Browny]

How many significant figures should we leave our answer to in the physics theory paper? I would be very thankful to any one who can give me a detailed explanation.

 

[Thought blocker]

Will come at night to solve everyone's doubt...
The people who asked me for Projectile motion formulas, here you go :

P R O J E C T I L E M O T I O N !​

Motion in two dimensions,
v and angle θ with
horizontal, upward is +ve

x-component → no acceleration
Vx = V cos Ø
x = Vxt = Vt cos Ø

y-component → acceleration is g
Vy = V sin Ø
y = Vyt − ½ gt^2
horizontal range → R =(V^2/g) sin 2Ø
max range at θ=45 deegree.



>>>>>>>MORE DETAILED VIDEO ON YOUTUBE<<<<<<<<​

 

[Thought blocker]

I M P O R T A N T E Q U A T I O N S !

This will help you all a lot
​

 

[princeali97]

http://papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Physics%20(9702)/9702_w10_qp_21.pdf

Question 2(a).. Why do we take tan for vertical component? Why not sin?
Explain please..
Markscheme: ( http://papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Physics%20(9702)/9702_w10_ms_21.pdf )

"The directory does not exist"-Link mein problem hai?

 

[raihann]

ok, i hav a question... in double slit experiment, will the dark fringe get lighter when we decrease the light intensity ? :O

 

[princeali97]

Can someone please send me some good labelled diagrams for the following questions.
Q:A loudspeaker produces a sound wave of constant frequency.Outline how a cathode-ray oscilloscope (c.r.o.) may be used to determine this frequency.(o/n 10 p23)
Q:The wave nature of light may be demonstrated using the phenomena of diffraction and interference.Outline how diffraction and interference may be demonstrated using light.In each case,draw a fully labelled diagram of the apparatus that is used and describe what is observed.(o/n 09 21)
Q:Outline briefly an experiment that may be used to demonstrate (i) diffraction of a transverse wave. (ii)Suggest how your experiment in (i) may be changed to demonstrate the diffraction of a longitudinal wave.(W08)
Q:The wave in (b) was produced in a ripple tank. Describe briefly, with the aid of a sketch.(w13 qp 23)
diagram, how the wave may be observed
QDescribe apparatus that demonstrates Brownian motion. Include a diagram.(s13 qp23)
Q:A ripple tank is used to demonstrate interference between water waves.
Describe(i) the apparatus used to produce two sources of coherent waves that have circular
wavefronts
Q:Experiment for determining Young Modulus.
Q-Demonstrating interfernce in i)microwaves ii)Water waves.
Q:Observing Stationary waves i)using a stretched string ii)Microwaves iii)Air column.
All these questions carry more than 4 marks and require some explanation too.I have done these questions in the past but i want to make sure what i will draw is correct.I will be very thankful to your response and I hope it helps others too.
Thank you.
Best of luck.

 

[thats_me]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s13_qp_21.pdf
5c How is it max at P? & how do we find the number of minima/maxima?

 

[omaaaar]

http://papers.xtremepapers.com/CIE/...and AS Level/Physics (9702)/9702_s09_qp_2.pdf
Q5 b part pls

 

[Thought blocker]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s09_qp_2.pdf
Q5 b part pls

Here you go Credits papajohn
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.

 

[omaaaar]

Here you go
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.

Thanks man got i had not understood this concept yet but got it now

 

[MiniSacBall]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s10_qp_21.pdf
Q2 b ii
I just don't know how did they get the speed from the graph!