Step 1: Use the definition of mutual inductance.
Mutual inductance is defined as
\[
M=\frac{\Delta \lambda}{\Delta I}
\]
where \(\Delta \lambda\) is the change in flux linkage and \(\Delta I\) is the change in current.
Step 2: Write the given values.
The change in flux linkage is
\[
\Delta \lambda=40\,\text{Wb}
\]
The current changes from \(0\) to \(16\,\text{A}\), so
\[
\Delta I=16-0
\]
\[
\Delta I=16\,\text{A}
\]
Step 3: Calculate mutual inductance.
\[
M=\frac{40}{16}
\]
\[
M=2.5\,\text{H}
\]
Step 4: Final conclusion.
Therefore, the value of mutual inductance is
\[
\boxed{2.5\,\text{H}}
\]