Question

If a toroid uses bismuth for its core, the field in the core compared to that in empty core will be slightly(a) greater(b) smaller(c) equal(d) None of these

Answer 1

(a) greater

because

for air,

B=μ. N I

and when any dielectric is used as core it becomes

B'= μ. K N I

clearly it is grater then the original