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Physics: Post your doubts here!

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The question says "describe what is seen..", yes you do talk about the smoke particles, but since they appear as tiny, white specks of light you should mention that in the answer to that question since it's an observation. Likewise you would mention that the motion of these specks of light is haphazard since that is also an observation.

thnx got it...and i also read that the smoke particles are not what you see but the light reflected from them....thnx sista!
 
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first here is how you convert the degrees and radians...
radians to degrees : multiply by 180/π
degrees to radians: multiply by π/180

Phase difference is simply is the fraction of the cycle (the angle) by which one wave moves behind the other.
you can calculate is by using this equation: (with degrees)
360 (x/λ) where x is the difference in the distance between the two waves...
or 360(t/T) where the waves are out of step by time t.
use 2π for radians, since 360 = 2π

For coherent waves....they have a constant phase difference...this is usually the case with waves fron the same source. It does not matter whether the waves are in phase ....but coherent waves must have a constant phase difference...which means that the difference between them is the same throughout. They must also have the same wavelength and the same frequency.
this is quite brief..but hope it helps.
after readin this i felt i know nothing about waves LOL!
 
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http://www.xtremepapers.com/papers/...nd AS Level/Physics (9702)/9702_w10_qp_21.pdf
http://www.xtremepapers.com/papers/...nd AS Level/Physics (9702)/9702_w10_ms_21.pdf
Q 2(b) and Q 6(a ii) Can someone show exactly how these both are drawn? i have read the mark scheme and examiner report but i might be thinking it is drawn some other way entirely so just to verify my own drawings.

http://www.xtremepapers.com/papers/...nd AS Level/Physics (9702)/9702_w09_qp_21.pdf
http://www.xtremepapers.com/papers/...nd AS Level/Physics (9702)/9702_w09_ms_21.pdf
Q 7(b) in this i also want to confirm if my drawing is correct so if someone else can show the correct one..
 
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Okay...

In the syllabus, we have:

(e) describe the effect of a uniform electric field on the motion of charged particles.

And in the notes, I have things like Equipotential Surface, Potential Gradient, and 'Electric field lines must meet the surface at right angles'.

... What in the realm of Physics is this?
 
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well 3 b is :
1) the sum of the forces in any direction must be zero
2) the sum of the moments of the force about a point must be zero
and if you mean 3 c ii....
1) quite simple...
M abut a point = force x perpendicular distance
= (30/100) x 150
= 45 Nm
2) it must be equal to the moments so it is also 45N
3) since the torque is 45Nm
and torque = one force x perpendicular distance
and we know that the perpendicular distance is 12/100 = 0.12 m
and the value of total torque is 45 Nm
so just substitute...
therefore Force = torque / perpendicular distance
= 45 / 0.12 = 375 N
The T is the mark scheme is tension which is the force caused by the string.
 
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well 3 b is :
1) the sum of the forces in any direction must be zero
2) the sum of the moments of the force about a point must be zero
and if you mean 3 c ii....
1) quite simple...
M abut a point = force x perpendicular distance
= (30/100) x 150
= 45 Nm
2) it must be equal to the moments so it is also 45N
3) since the torque is 45Nm
and torque = one force x perpendicular distance
and we know that the perpendicular distance is 12/100 = 0.12 m
and the value of total torque is 45 Nm
so just substitute...
therefore Force = torque / perpendicular distance
= 45 / 0.12 = 375 N
The T is the mark scheme is tension which is the force caused by the string.
sorry for wasting ur time, u explained the wrong question i meant 4 b iii..i am so sorry bro :/ thank u though .
 
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