Concept:
For the parabola:
\[
y^2=4ax
\]
the length of the latus rectum is:
\[
4a
\]
Step 1: Given parabola:
\[
y^2=4ax
\]
It passes through the point:
\[
(3,2)
\]
Step 2: Substitute \(x=3\) and \(y=2\).
\[
2^2=4a(3)
\]
\[
4=12a
\]
\[
a=\frac{1}{3}
\]
Step 3: Length of latus rectum is:
\[
4a
\]
\[
4a=4\left(\frac{1}{3}\right)
\]
\[
4a=\frac{4}{3}
\]
Therefore,
\[
\boxed{\frac{4}{3}}
\]