#### Benzoate

1. Homework Statement
Deduce an approximation for Planck's radiation law: To what what wavelength does hv/kT=1

2. Homework Equations
Wien Distribution equation
B(lambda)= 2hc^2/lambda^5*exp(-hc/kT(lambda))
Rayleigh-jeans approximation
B(lambda)=2ckT/lambda^4
3. The Attempt at a Solution
My main concern is with the latter part of the question: To what wavelength does hv/kT=1?

My first attempt at finding a wavelength was to equate Rayleigh-jeans approximation equations and the Wien Distribution equations to each other.

(2hc^2/lambda^5)*exp(1/lambda) = 2ckT/lambda^4 . Then to eliminate T from the equation , I would set T= hv/k. Therefore 2ck(hv/k)/(lambda)^4 = 2hc^2/(lambda)^5*(exp(-1/lambda) => lambda=c/2/v. The only problem is , I still have an unwanted unknown, which is the frequency. Do you need the frequency in order to determine the wavelength?

Related Introductory Physics Homework Help News on Phys.org

### Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving