OCR Physics B G495 Field and Particle Pictures June 21st 2011 Exam Thread

path difference = n xlambda (for constructive interference) Path difference = (0.5+n)lambda (for destructive interference.)

The second equation is definitely something they will ask us to derive but it comes from E= p^2/2m, lambda = h/p and lambda = 2d/n - like you said

Anyone got some random physics questions (from g495) to ask me?

thought id let you know im pretty certain youl be getting an A* if theres any justice in the world! also thanks for all your help :-)

oh and meridian, does it go directly through the centre of the earth or like via the circumference?

Why are we expected to know "estimates" for the radius of a Carbon-12 nucleus?

In the practise advanced notice article questions, one question is: For practical purposes, the BIPM suggests use of a Helium-Neon laser for establishing the length of a meter. The wavelength of the lasers, ?HeNe,, is accepted as being 632.99139822 nm. If an atomic clock based wave counter is used that is capable of counting individual waves, how many waves would pass in one second? (The device will only provide a whole number count.)

Caqn anyone answer this for me??

Oblateness is basically an irregular sphere, in this case a sphere that bulges equatorially, and as consequence the north and south pole squash together. The reason, based on my understanding, for this is because when the earth is rotating the gravitational force from the centre of mass is greater - in order to provide a cetripetal force that causes the elements in the earth to rotate, the gravitational force must be greater than the force due to the pressure difference from the Earth's fluid mantle.

Th radius of the nucleus of Carbon-12 is approcimateloy the same as the radius of other nuclie. This is always around 10^-14 m, while the radius of the WHOLE atom i about 10^-10m

I too was a bit stuck on this question; it doesn't make any sense really Like REALLY doesn't make any sense.

If anyone's done the January 2011 past paper could someone explain question 10.c) please.

Link is: http://www.johnbright.conwy.sch.uk/depts/science/Y13/P-Y13_Past_Papers.html

Have no idea why the MS has made the ratio rise to the power 3.

If the force due to gravity is larger at the equitorial plane than the force due to the pressure difference, why does it bulge at the equator?
I'm a little confused :P

Haha glad I'm not the only one lol I thought that that the waves that pass in one second is just the frequency so you would use v = f(lambda) and then v/(lamda) = f so you would do (3 x 10^8)/(632.99.... x 10^-9) but they just did one over the wavelength??

is anyone else finding time to be a bit of struggle for these papers?

can someone please help me with 9)d)i) from last years paper:

http://www.johnbright.conwy.sch.uk/depts/science/Content/Past_Papers/Y13/Physics/G495Jun10.pdf

i dont get how the half lives is 4.

Although in practice more like 80-85 for an A*, 70-75 for an A etc.

100/(2^n)=6.5
Where n = number of half lifes
2^n=(100/6.5)
n*ln2=ln(100/6.5)
n=(ln(100/6.5))/ln2
n= 3.94