I am trying to use Mathematica to plot the following equation $E(q,\Delta)$ vs $qa$, for set values of $ D \Delta/a^2$ and $\bar\rho a/D$. I have looked at other stackexchange posts which deal with transcendental equations and Bessel functions, but none have explained exactly what I am trying to do.

Where $ \beta _{nk} $ is defined by the transcendental equation:

$\Large \beta_{nk}\frac{J'_{n}(\beta_{nk})}{J_{n}(\beta_{nk})}=-\frac{\bar \rho a}{D}$

Here is the code for the first equation:

E1[q_, \[CapitalDelta]_, rho_, k_, D_, a_, n_] := (4*Exp[(-((B0k[k])^2)*D*\[CapitalDelta])/a^2]*(B0k[k])^2/(((rho*a)/D)^2 + (B0k[k])^2)*((q*a) (-BesselJ[0, q*a]) + rho*BesselJ[0, q*a])^2/(q*a^2 - B0k^2)^2) + (8*Exp[(-((B[n, k])^2)*D*\[CapitalDelta])/a^2]*(B[n, k])^2/(((rho*a)/D)^2 + (B[n, k])^2 - n^2)*((q*a)*BesselJ[n, q*a] + (rho*a)/D*BesselJ[n, q*a])^2/((q*a)^2 - B[n, k]^2)^2) 

I can plot the transcendental equation, but can't figure out how to find the solutions in such a way that I could incorporate them into the other equation.

Plot[B*(-BesselJ[1, B])/BesselJ[0, B], {B, -10, 10}]