Answer
$I_{ab} = 0 A $
The equivalent current source is $5A$.
Work Step by Step
The two points, a and b, are not connected within a closed loop. Thus, it follows that the current through them is $\fbox{0A}$. We now must find the equivalent current source. Thus, we use Ohm's law to find the equivalent current:
$I = \frac{V}{R} = \frac{10V}{2 \Omega} = \fbox{5A}$
Thus, the equivalent current source has a current of 5 Amps.
