In a science-fair project a student needs the magnetic field at a point 3 cm from a…
PHYSICS · Multi-part · CBSE · Physics · Magnetic Effects of Electric Current · Magnetic Effects of Electric Current
Problem
In a science-fair project a student needs the magnetic field at a point 3 cm from a straight conductor to be at least four times stronger than the magnetic field that existed at 6 cm from the same conductor when it was carrying 2.5 A.
(i) For the original current of 2.5 A, calculate the ratio of the magnetic field strengths at 3 cm and 6 cm from the conductor.
(ii) Determine the minimum current the student must set in the conductor so that the magnetic field at 3 cm satisfies the required condition of being four times the original field at 6 cm.
(iii) The student then places a second identical straight conductor parallel to the first and 3 cm away from it, each carrying the current found in part (ii) in the same direction. Calculate the magnitude of the magnetic field at the point exactly midway between the two conductors and explain how the presence of the second conductor affects the field at that point.