Toroid MCQ - Practice Questions & Answers

Solve by difficulty

An iron-cored toroid has a ring of radius $7cm$ and the number of turns $500.$ If $2A$ current is passed through the wire, what will be the value of the magnetic field on the axis of the toroid? Given, the relative magnetic Permeability of Iron $=1500$

$4.28wb.m^-^2$

$3.5wb.m^-^2$

$2.98wb.m^-^2$

None of the above

View Solution

Concepts Covered - 1

Toroid

Toroid -

If we try to bend a solenoid in the form of a ring then the obtained shape is a Toroid. So, a toroid can be considered as a ring shaped closed solenoid. Hence it is like an endless cylindrical solenoid. From the given figure we can understand Toroid much better.

Now to obtain the magnetic field by an toroid, let us consider a toroid having N turns.

Here, we will now apply Ampere circuital law to calculate magnetic field of a toriod. Suppose we have to find the magnetic field B at a point P inside the toriod as shown below in figure -

Let us take an amperion loop which is a circle through point P and concentric inside the toriod. By symmetry field will have equal magnitude at all points of this circle and this field is tangential to every point in the circle
Thus,

$\begin{array}{l}{\oint B . d l=\mu_{0} \mathrm{NI}} \\ {\text { or, }} \\ \\ {2 \pi r \mathrm{B}=\mu_{0} \mathrm{NI}} \\ {\text { or, }} \\ \\ {\mathrm{B}=\frac{\mu_{0} \mathrm{NI}}{2 \pi r}}\end{array}$