Answer
$J=6.54\times10^{-7}\frac{A}{m^2}$
Work Step by Step
We know that $J=nqv_d$
$n=\frac{8.70}{cm^3}=\frac{8.70}{(10^{-2}m)^3}=8.70\times10^6m^3$
So, we obtain:
$J=8.7\times10^6\times1.6\times10^{-19}\times4.70\times10^3$
$J=6.54\times10^{-7}\frac{A}{m^2}$
