If we use the rough energy/temperature relationship:
E \approx k_B T
And we know the energy of a photon is related to wavelength as so:
E=\frac{h c} {\lambda}
Then combining these two formula we get:
\lambda \approx \frac{h c} {k_B T}
Plugging in for T=2.7K
That gives us \lambda \approx...
Using the FRW:
\left( \frac {\dot{a}} {a} \right)^2 = \frac {8 \pi G \rho} {3} - \frac {k c^2} {a^2}
We define critical density by setting k = 0 and rearranging to get:
\rho_c = \frac {3 H^2} {8 \pi G}
Where:
H = \left( \frac {\dot{a}} {a} \right)
My question is does \rho include the...
Hi there,
Could somebody explain how illumination - by which I mean flux per unit area - depends on the mirror diameter of a telescope and/or its focal length?
Is this different for point objects like stars and for extended objects like nebulae?
Thanks in advance,
Nick :-)
Firstly, lower notes have lower, not higher, frequencies.
Looking at the equation:
wavespeed = frequency * wavelength
Since all sound waves travel approximately at the same speed (340 metres per second) this means that low notes must have long wavelengths.
In Summary:
LOW NOTES = LOW...
I don't know if it's just my browser but there's a bit of my previous post that is doesn't seem to be able to process correctly. Here are those two lines again:
Now we integrate theta from 0 to pi as mentioned before:
V = \frac {2 \pi} {4 \pi \epsilon_o} \sum_{l=0}^{\infty} r^l R^{1-l}...
Homework Statement
Electric Charge is distributed over a thin spherical shell with a density which varies in proportion to the value of a single function P_l(cos \theta) at any point on the shell. Show, by using the expansions (2.26) and (2.27) and the orthongonality relations for the...
Hi!
What you've done looks pretty good, but after subbing in the limits from the integral on this line:
\frac { \lambda } { 4 \pi \epsilon_o} ( ln (x_o + L/2) - ln (x_o - L/2) )
instead of combining the logs (using ln(A) - ln (B) = ln (A/B) ) like you've done on the next line, why...
Homework Statement
The polarization charge on the surface of a spherical cavity is - \sigma_e cos(\theta) at a point whose radius vector from the centre makes an angle \theta with a given axis Oz. Prove that the field strength at the centre is \frac {\sigma_e}{3 \epsilon_o} parallel to...