Problem 5: Since moving charges create magnetic fields and magnetic fields exert forces on moving charges, devices that are used to measure field strengths often affect the system they are being used to measure. Consider the wire segment in the figure, which is used to measure the magnetic field by determining the force exerted on the current flowing through it. Oo 20.0 cm Part (a) Estimate the field the loop creates by calculating the field strength, in teslas, at the center of a circular loop 20.0 cm in diameter carrying 4.5 A. Numeric: A numeric value is expected and not an expression. B = Part (b) What is the smallest field strength this loop can be used to measure with a 4.5-A current, if its field should alter the measured field by 0.0100% or less? Numeric A numeric value is expected and not an expression. B =