MCQ Detailed View

A toroid is a coil of wire shaped like a ring or doughnut, with current flowing through its turns. It is used in physics and electrical engineering to create a magnetic field that is mostly confined inside the ring.

The magnetic field inside the core of the toroid (the space where the wire loops are wound) is strong and depends on the current in the wire and the number of turns. However, in the open space outside the toroid, there is no magnetic field. This happens because the magnetic field lines are closed loops confined inside the toroid, and the circular symmetry cancels the field outside.

In simpler terms, if you are outside the doughnut, the magnetic field is effectively zero, even if a current is flowing inside. This property makes toroids useful in electrical devices because they reduce interference with nearby circuits.

The strength of the magnetic field inside the toroid can be calculated using the formula:

B=μ0NI2πrB = \frac{\mu_0 N I}{2 \pi r}B=2πrμ0NI

where $B$ is the magnetic field, μ0\mu_0μ0 is the permeability of free space, $N$ is the number of turns, $I$ is the current, and $r$ is the radius of the loop. But this formula applies only inside the core; outside the toroid, the field is zero.

This concept is part of Physics, especially in electromagnetism, and helps in understanding how coils, inductors, and transformers work.

So the correct answer is Zero, as there is no magnetic field in the open space outside a toroid.