A thin, circular coil of wire of radius r consists of 100 turns of wire carrying a conventional current of I in the counter-clockwise direction. The magnitude and direction of the magnetic field at the center of the coil is:

The magnitude of the magnetic field is (50μ₀I/r) T or 6.28 × 10^-5(I/r) T.

At the interior region of the coil, the magnetic field will be outward and the exterior region of the coil, the magnetic field will be inward

Explanation: For the magnitude of the magnetic field, please see the attachment below.

The direction of the magnetic field can be determined using the right hand rule, if you place your fingers (excluding the thumb) on a circle to point in the counter-clockwise direction, your thumb will point outwards; and when the thumb moves around the coil, it will point inwards. The direction of the magnetic field is denoted by the thumb.

Hence, at the interior region of the coil, the magnetic field will be outward ( out of the plain) and the exterior region of the coil, the magnetic field will be inward (into the plain)

the part of the wave he is travelling on is the crest

resonant frequency