Plug it in to the math equation
Ok, so we have this equation: $γ(R)=γ_0+(Av_f)/R$
First, we substitute the values into the equation that we know.
$γ(R) = (5\cdot10^{12}) + (3/4\cdot1.39\cdot10^6)/R$. Simplified, this is:
$γ(R) = (5\cdot10^{12}) + (1.0425 \cdot 10^6)/R$
$γ(R)$ can be measured in your experiment. Then we can solve your equation for $R...$
$\large{R = \fbox{$\frac{1.0425 \cdot 10^6}{γ(R) - 5\cdot10^{12}}$}}$
Plug in your value of $γ(R)$, and you're there!*
*In other words, how should I use the λmax obtained through the experiment in the provided equation?
The equation only mentions $\gamma (R)$, I don't know how to help you there**
**Zhe: @JavaScriptCoder For these types of questions, the first thing to ask is "do you work in a lab?"
If not, why are you doing experiments outside of a lab, and if so, why is it that no one in your lab has any expertise on this?