Physics: Post your doubts here!

[biscuitbiscuit]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_s11_qp_21.pdf
Q5 (b), someone please solve it

 

[Tulaib]

plz can someone explain me mcqs 8, 18, 23, 25 ,29 ,30 of s12_qp12??????

 

[mehria]

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s11_qp_21.pdf
Q5 (b), someone please solve it

Note that we r asked to find I2 i.e. the current across a fixed resistor..
so maximum current will be:- V/R= 12/6 = 2.0 A
and i think that the minimum current value is zero just bcuz if we take the value of the variable resistor less than the value of fixed resistor then all the current will flow through the low resistance loop giving zero reading on the ammeter for the second loop

 

[Sam Ivashkov]

Hi, I was doing this paper http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w12_qp_12.pdf and I got stuck hardcore on question 37. The answer should be C apparently but it makes no logical sense to me. Can someone explain it to me?

 

[mehria]

Hi, I was doing this paper http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w12_qp_12.pdf and I got stuck hardcore on question 37. The answer should be C apparently but it makes no logical sense to me. Can someone explain it to me?

the answer is C becuz here we have 2 resistors that will half the value of the current...
Suppose that the value of one resistor is 2 ohms n the voltage supply is 12V
so for first circuit current will be:- 12/2= 6A
while for the second circuit it will be:- 12/4=3A (NOTE: resistors are in series so they will add up to 4)
thats the reason y the current value won't remain the same..so it is incorrect

 

[Namehere]

Hi, I was doing this paper http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w12_qp_12.pdf and I got stuck hardcore on question 37. The answer should be C apparently but it makes no logical sense to me. Can someone explain it to me?

Maybe you didn´t read the question properly? They are asking for which row is NOT correct. Maybe that´s why you dont understand why the answer is C? The answer is C because it´s wrong! - Thats what they are asking for!

 

[Suchal Riaz]

plz can someone explain me mcqs 8, 18, 23, 25 ,29 ,30 of s12_qp12??????

thats the most rude thing i see over here.
atleast post the link of the paper when you ask question. It's written on the first page in bold that post the link.

 

[Thought blocker]

Maybe you didn´t read the question properly? They are asking for which row is NOT correct. Maybe that´s why you dont understand why the answer is C? The answer is C because it´s wrong! - Thats what they are asking for!

That happened with me

 

[Suchal Riaz]

plz can someone explain me mcqs 8, 18, 23, 25 ,29 ,30 of s12_qp12??????

 

[biscuitbiscuit]

Note that we r asked to find I2 i.e. the current across a fixed resistor..
so maximum current will be:- V/R= 12/6 = 2.0 A
and i think that the minimum current value is zero just bcuz if we take the value of the variable resistor less than the value of fixed resistor then all the current will flow through the low resistance loop giving zero reading on the ammeter for the second loop

Thanks

 

[mehria]

Thanks

np

 

[Suchal Riaz]

Tulaib
power=IV = 32*230=7360 J/S
mass/second * g * height = weight*height/second=power
so 200*9.81*8=15696
efficiency = 7360/15696=0.469=46.9%~47%

 

[Tulaib]

View attachment 39040

thats the most rude thing i see over here.
atleast post the link of the paper when you ask question. It's written on the first page in bold that post the link.

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_s12_qp_12.pdf
now can u solve the others plz?

 

[Suchal Riaz]

Tulaib

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s12_qp_12.pdf
now can u solve the others plz?

would you give me enough time. thats the second most rude thing i have witnessed.

 

[Suchal Riaz]

Tulaib
Q23
pressure of water = rho g h = 0.5X10^5
pressure of gas = pressure at point below 5 m of water = pressure of water + atmospheric pressure = 0.5 + 1.0 X10^5 = 1.5X10^5 Pa

 

[Tulaib]

Tulaib
Q23
pressure of water = rho g h = 0.5X10^5
pressure of gas = pressure at point below 5 m of water = pressure of water + atmospheric pressure = 0.5 + 1.0 X10^5 = 1.5X10^5 Pa

y cant we use 7 m here?

 

[Suchal Riaz]

Tulaib
Q25
as wire is of same material the E is same
E = stress/strain = (F*original length)/(A*extension)
extension = (F/EA )*original length
so extension is directly proportional of length and inversely proportional to A
area is squared of diameter(multiply by 1/4 pi but thats a constant)
so extension is directly proportional of length and inversely proportional to square of d
as the diameter is 1/2 the extension increase by 4
length is 1/4 so extension decrease by 1/4
8 * 1/4 * 4 = 8

 

[Suchal Riaz]

y cant we use 7 m here?

it's h which means vertical distance. we've done this at o levels.
here is an example that pressure is affected by height alone.

 

[Tulaib]

it's h which means vertical distance. we've done this at o levels.
here is an example that pressure is affected by height alone.

I have an A* in O level phy, was unsure about h, so posted my doubt -_-

 

[Suchal Riaz]

I have an A* in O level phy, was unsure about h, so posted my doubt -_-

no problem. i was just telling you that it was in o level as well.
if you want the complete reason see the derivation of rho g h which is indeed in our syllabus
sorry for very rough drawing. it's a pain to draw in paint: