# Relation between current (not at saturation) and voltage in photoelectric effect

This is the question I got for an assignment.

How do I determine stopping potential from this data? I can see that the relation between $$V$$ and $$I$$ seems to be linear, so can I just use the equation of a line between $$V$$ and $$I$$ to find the stopping potential? Or is there another way to solve the question?

My main question, however, is: Is the relationship between $$V$$ and $$I$$ actually linear?