Recent content by vincentchan

1. Why don't you just regard the microwave as a very quick changing E field... The water molecule is just a electric dipole flipping in the changing E field... Does that solve your problem? 2. How do they keep the microwave frequency photons from escaping the oven if visible light can get...

This is not a physics problem, instead, this is related to the human eyes... Human eyes have 3 different color sensor(red, green and blue), every wavelength in the visible light will turn on 1 or more color sensor... The reason you see 7 color in rainbow is because there are 7 different...

Your question has been answered, digest what people say. Guassian Law is always valid no matter how you choose the surface.. ... a simple graph will help clearify your idea...

So, Do we fully understand the weak interection? I mean, if we understand weak interaction, we should able to predict the lifetime of muon, right? But it seems like weak interaction is not as good as QED... can anyone tell me why...?

how about the life time of muon, can QED predict the lifetime of muon with a high accuracy?

because in the triangle wave, V is proportional to t... and V^2 is proportional to t^2, when you do the RMS, you need to take the squreroot of \int V^2 dt , this is where the root 3 come from

I have a little question about QED.. How come QED could precisely predict the magnetic moment of electron and muon, but can't predict the lifetime of neutron with the same accuracy?

do you mean time delation here? retarded time in relativity means the other thing... Well, the answer is NO , However, in fact, the time delation affects the light in the other way. i.e. frequency... Have you heard about red shift? Can you use time delation in gravity field to explain it?

well, after the integration, you will get his equation: U=-\frac{Gm_1m_2}{r} whereas the r is the redius of the moon as UrbanXrisis suggest...

\int^h_x Axdx = \int^x_0 Ax dx solve for the x... h is the height of the cone, and A is the cross section area of the cone...

since n is integer, find all the factors of 60, which are 2,3,4,5 and see which 3 consecutive numbers satisfy n(n-1)(n-2)=60

do you know the fact that \lim_{x \rightarrow 0} \frac {sinx}{x} =1 if yes, you should start from here

expand tanx in taylor series, and do what you should do...

This link might help http://www.mph.net/coelsner/calcapps/cone_ex.htm what you need to do is basically find the volume of the cone and multiply by its density to get its mass...

the Force is related to the current and the B field by: F=LIxB... L is the length of the wire I is the currect B is the B field the bold letter means vector in my notation...