physics mcq help needed! urgent!

[mz]

cie physics paper 1 , november 06, question 21...please help quickly!

[[Spy]]

yes please me tooo
what a question -.-

[mz]

yes please me tooo
what a question -.-

exactly.....why have they not taken atmospheric pressure into consideration??? this is silly...

[halosh92]

2 min

[halosh92]

total pressure = 17.5 * 10^6
therefore
pressure of water + pressure of oil = total pressure
phg+phg=total pressure
1000*(2000-x)*9.8  +  830*x*9.8=17.5*10^6
just arrange the formulas
it will be around 1260 whis nearest to the answer D

[halosh92]

i have these doubts too
june 2006 p1
Q33
Q24
Q25
Q28

[[Spy]]

why is total pressure 17.5* 10^6?

[nid404]

why is total pressure 17.5* 10^6?

it's mentioned in the question

[halosh92]

why is total pressure 17.5* 10^6?

because its MPa mega Pascale
u have to change to pascale so *10^6

[halosh92]

for 2009 oct/nov  p12
Q12

[nid404]

i have these doubts too
june 2006 p1
Q33
Q24
Q25
Q28

Q24)intensity=ka². using numericals would be helpful here
consider a=2 and k=1  I=4
if I has to be 8  a will be = 4? NO  less than 4. This is the case with any wave....the formula is important. I =ka²
And half the frequency means twice the wavelength.  Hence B

Q25) calculate the wavelength first.

w= v/f =  340/500=0.68m

0.68m= 2
0.17= ?
0.17X 2
--------------------
0.68

=1/2 radians
So B

[nid404]

Q28) 

a=distance between the slit
=wavelength
x=fringe spacing
D=distance from screen

x is initially =4mm

now the slit spacing is halved so 1/2 a
D is doubled and is now 2D

wavelength is constant

earlier x= ( D)/ a

now x= (2D)/ 1/2a

x is 4 times greater

so x is 4X4=16mm

[nid404]

Q33)


V=12V

It is same in both parallel wires.

it splits depending on the ratio of the resistor. Greater the resistance, more the voltage across it.

in first wire

across 500= 500/1500 X 12= 4V [X]

in the second wire

across 2000=2000/3000 X12=8V [Y[

p.d between the 2 points X and Y = 4V

[[Spy]]

i have these doubts too
june 2006 p1
Q33
Q24
Q25
Q28

Q24) since intensity is directly proportional to amplitude SQUARED then the sqaure root of intensity is proportional to amplitude, and therfore if the intensity is double then the intensity has to increase by a square root of 2, and the frequency is halfed therfore each wave takes double the number of squares, which means its B

Q25) the wavelength is equal to 340/500= 0.68

and it ask for the phase difference between two points on the SAME WAVE, and since the wavelength is 0.68, and the two points are 0.17 apart then its 0.17/0.68, then you have to multiply it by 360, this gives 90 degrees, and since pie is equal to 180 then the answer is B pie/2

Q28) we know that wavelength/distance between slits is = distance between two fringes/distance to screen

and therefore we want to know the relation between the distance between two fringes and the slit spacing therefore we have to re arrange the equation so that they are on different sides of the equation, but the equation already satisfies that and therefore, when the distance between the slits halfs the distance between 2 fringes has to double as they are inversely proportional because one is numerator and the other is denominator, and therefore that gives us a fringe spacing of 8, but then the distance to screen doubles, arranging the equation to make the distance to the screen on the left hand side we see that is directly proportional to the fringe spacing and therfore as it doubles the fringe spacing has to double to giving us 16mm

[halosh92]

thankyouuuu so much both of u.
may june 2007
Q7
Q10
thx ^^