A toroidal core of uniform cross-section is made from two equal-length semicircular…
PHYSICS · Single correct · A Level · Physics · Fields and their consequences · Fields and their consequences
Problem
A toroidal core of uniform cross-section is made from two equal-length semicircular pieces: material X with μr=500 and material Y with μr=2. A steady current in the surrounding coil produces a uniform magnetizing field H throughout the toroid. Which statement about the magnetic flux density B in the two materials is correct?
(a) B in material X is 500 times larger than in material Y because material X has a relative permeability of 500.
(b) B is the same in both materials because the magnetic flux must be continuous around the closed path.
(c) B in material X is 250 times larger than in material Y.
(d) B is larger in material Y because the lower permeability allows more flux to build up there.