# Help, not sure?

1. Feb 13, 2005

### dranger35

I was given this problem, but I dont know where to start?

R(v) = dE/dv = (8(pie)(h)(v^3)/ (c^3(e^(hv/kT-1))).
Recall that if you want the energy per unit wavelength, you cannot
simply replace the argument v with c/wavelength. Instead you must write
R(wavelength) = dE/dv = (dE/dv)(dv/d wavelength).

Evaluate R().

Any help is appreciated!!

2. Feb 13, 2005

### dextercioby

You have to replace both the frequency and its differential.

Daniel.

3. Feb 13, 2005

### dextercioby

And the last formula that u've written,it should have been
$$\frac{dE}{d\lambda}=\frac{dE}{d\nu}\frac{d\nu}{d\lambda}$$

Daniel.