Four infinitely long straight conductors are fixed along the four sides of a square…
PHYSICS · Multi-part · AP · Physics C: Electricity and Magnetism · Magnetic Fields and Electromagnetism · Magnetic Fields and Electromagnetism
Problem
Four infinitely long straight conductors are fixed along the four sides of a square of side a lying in the plane of the page. Each conductor carries a steady current I in the anticlockwise sense around the square.
(i) Obtain an expression for the magnitude of the magnetic field produced at the centre of the square by one side and hence determine the net magnetic field at the centre when all four currents are anticlockwise.
(ii) The currents in the two horizontal sides are now reversed while the currents in the two vertical sides remain unchanged. Calculate the magnitude and direction of the resultant magnetic field at the centre.
(iii) Keeping the currents in the vertical sides equal to I, determine the value of current that must be sent through each horizontal side (direction to be chosen suitably) so that the net magnetic field at the centre becomes zero.