question_answer

The magnitude of magnetic induction for a current carrying toroid of uniform cross-section is

A)  uniform over the whole cross-section

B)  maximum on the outer edge

C)  maximum on the inner edge

D)  maximum of the centre of cross-section

Correct Answer: A

Solution :

                A toroid can be considered as a ring shaped closed solenoid. Hence, it is like an endless cylindrical solenoid. Consider a torojd having n terms per unit length magnetic field at a point P in the figure is given as \[\beta =\frac{{{\mu }_{0}}NI}{2\pi r}={{\mu }_{0}}nI\] Where,                 \[n=\frac{N}{2\pi r}\] Hence, the magnitude of magnetic induction for a  current   carrying   toroid   of   uniform cross-section is uniform over the whole cross-section.