The reading of the ammeter for a silicon diode in the given circuit is:

Given, $R=200 \mathrm{\Omega }$ and $V=3 \mathrm{V}$. We have to calculate the current. We know that, a potential barrier across silicon diode $=0.7 \mathrm{V}$.

$V=IR$$\Rightarrow I=\frac{3-0.7}{200}=0.0115 \mathrm{A}=11.5 \mathrm{mA}$

So, the current is $11.5 \mathrm{mA}$.