Tagged Questions
4
votes
3answers
342 views
Why do we still not have an exact definition for a kilogram?
I read that there is an effort to define a kilogram in terms that can exactly be reproduced in a lab. Why has it taken so long to get this done? It seems this would be fairly important.
Edit
Today I ...
2
votes
3answers
479 views
How is Planck's law defined?
Now, I found three different definitions of Planck's law:
$$
P_1(\nu,T) = \frac{8 \pi}{c}\frac{h \nu^{3}}{c^2} \frac{1}{e^{h\nu/kT}-1}
$$
$$
P_2(\nu,T) = 2\frac{h \nu^{3}}{c^2} ...
