Physics: Post your doubts here!

[Mairaxo]

okay you're a genius! thanks so much

hahah no problem

 

[zackle09]

Q30- d sin theta=n lambda
sin theta=1 as its normal to the grating. then d=1/N. N=300 per mm means 300000 per m. so 1/300000=(690*10^-9)*n
n will be around 4. then multiply by 2 and u get 9

how come you multiply it by 2?

 

[Mairaxo]

how come you multiply it by 2?

you always multiply by 2 to find the maxima. i think it was because n is only for one side or something...i dont really remember the reason but just remember 2 do it everytime

 

[zackle09]

you always multiply by 2 to find the maxima. i think it was because n is only for one side or something...i dont really remember the reason but just remember 2 do it everytime

and for 27..if the diameters being halved shouldnt it be 1/2?

sorry can you do 36 as well..last question

 

[Mairaxo]

and for 27..if the diameters being halved shouldnt it be 1/2?

sorry can you do 36 as well..last question

no diameter gets halved but the radius gets decreasd by 1/4th then. Try it using a value for diameter and find the area. Then repeat using half value of diameter. Area will be 1/4th

 

[Mairaxo]

and for 27..if the diameters being halved shouldnt it be 1/2?

sorry can you do 36 as well..last question

you have to split it into 2 parts. 1st take the positive part. I=2. then find P. P=I^2R=2*2*100=400W
then take the negative part where I=-1. P=-1*-1*100=100
then average it as they want the mean power. so 100+400/2=250W

 

[Ahmedraza73]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w10_qp_12.pdf
Can any one help me with the Question No:7,15,22...
Please anyone

 

[Tkp]

http://papers.xtremepapers.com/CIE/...nd AS Level/Physics (9702)/9702_w10_qp_12.pdf
Can any one help me with the Question No:7,15,22...
Please anyone

ok for 15 take f=kv
mg=kv
make v the subject
mg/k
and substitute in the formula .5mv^2
u will get the ans D

 

[Ahmedraza73]

ok for 15 take f=kv
mg=kv
make v the subject
mg/k
and substitute in the formula .5mv^2
u will get the ans D

why should i subtitute with 5mv^2?
Expalin

 

[Tkp]

Damn dnt u knw the formula of kinetic energy .5 mv^2

 

[Ahmedraza73]

Damn dnt u knw the formula of kinetic energy .5 mv^2

bro that :1/2 m v^2
and you wrote 5 mv^2: nnow what does this mean

 

[Tkp]

aha lol
i wrote .5
which is 1/2
lol

 

[adibshamsuddin]

M/J/12 paper 12 questrion no 30. If anyone can help, I would be very obliged.

 

[daredevil]

M/J/12 paper 12 questrion no 30. If anyone can help, I would be very obliged.

link pls

 

[ahmed abdulla]

1__Two springs P and Q both obey Hooke’s law. They have spring constants 2k and k respectively.
The springs are stretched, separately, by a force that is gradually increased from zero up to a
certain maximum value, the same for each spring. The work done in stretching spring P is WP,
and the work done in stretching spring Q is WQ.
How is WP related to WQ?
A WP =
 1/4 WQ B WP =1/2
 WQ C WP = 2WQ D WP = 4WQ
i get C ... but the answer is B


2___A wave of amplitude a has an intensity of 3.0Wm–2.
What is the intensity of a wave of the same frequency that has an amplitude 2a
A_12 .. i used I>A^2 and still not coming​

 

[ahmed abdulla]

??

 

[hellangel1]

http://papers.xtremepapers.com/CIE/Cambridge%20International%20A%20and%20AS%20Level/Physics%20(9702)/9702_w09_qp_11.pdf
Question 22 and 26 please!

 

[adibshamsuddin]

9702_s12_qp_12.pdf

 

[freakybandi]

hey how do we connect the GM tube in a circuit? like
http://papers.xtremepapers.com/CIE/...and AS Level/Physics (9702)/9702_s03_qp_5.pdf
qs2? how do we make the diagram?

 

[Tkp]

M/J/12 paper 12 questrion no 30. If anyone can help, I would be very obliged.

see the cro rises to a maximum at a position X, falls to a minimum and then rises once again to a maximum at a
position Y. so the distance between the adjacent antinodes is .5lambda
so 33*2/100=lambda
v=flambda
and f is 500
so the time base for 1 div is .5ms
so it takes 4 div to complete a wave that means 4*.5
=2 ms
2/1000=1/500
and f=1/t
so it matches and the ans is B
Hope ur clear nw