Equation 29-4 gives the magnitude B of the magnetic field set up by a current in an infinitely long straight wire, at a point P at perpendicular distance R from the wire. Suppose that point P is actually at perpendicular distance R from the midpoint of a wire with a finite length L. Using Eq.29-4 to calculate B then results in a certain percentage error. What value must the ratio L/R exceed if the percentage error is to be less than 1.00%? That is, what L/R gives (B from Eq.29-4) – (B actual)/ (B actual) x (100%) = 1.00%?