The maximum of the planck radiation curve vs wavelength is satisfied when      x = 5 - 5 exp(-x),
where x = hc/(kT)/wavelength.

• Suggestions
• type 'x' in cell A3
• enter '2' in cell B3
• type 'expr' in cell A6
• enter '=5-B3-5*exp(-B3)' in cell B6
• Bring up Solver under Tools
• Follow the instructions and see if it converges to the answer of 4.965..
• Now try an initial x value of 15 and try again.
• Next try an initial x value of -4 and see what happens
• Solver is quite general and can be helpful in many different situations
• But ... it can fail if you don't start in the right vicinity.
• When you are searching for a solution in which 2 or 3 variables are being adjusted, it becomes more important to start in the right neighborhood.

• Bring up the DecayData.xls spreadsheet
• This has decay rate vs time in the lefthand columns
• An equation on the sheet reminds you of how count rate depends on the decay constants and initial parameters
• You need to construct a column of calculated decay rates in column D as a function of time
• Column E will contain the difference between columns C and D, squared
• You will want to minimize the sum of all the squared differences
• Solver will do this if you tell it to adjust the four parameters and find a minimum
• For silver the decay constants are ln(2)/144 = .0048 and ln(2)/25 = 0.0277, roughly.
• The background count rate is assumed negligible or already folded into the data.