Magnetic fields A circle of wire will create a magnetic field inside and outside

Question

Magnetic fields

A circle of wire will create a magnetic field inside and outside the circle. In general, the magnetic field of a single coil of N turns of wire can be written where B_z is the magnetic field in the axial direction, mew_0 is a constant, I is the current in the coil, N is the number of turns in the coil, R is the radius of the coil, and z is the distance along the axial direction. Notice that this equation only describes the magnetic field in the axial direction. In addition, this equation only describes the magnetic field on axis (along the z-axis itself, not just in the z-direction). In this activity, the x-direction and y-direction are held constant. Mathematically, the generation of a magnetic field by a current-carrying wire is represented by the Biot-Savart law. Equation 5.1 comes from the Biot-Savart law, but is not identical to it. The magnetic field of two coils can be found using the superposition principle, a concept you saw last semester during your studies of torque. What is the physical position that corresponds to z = 0? What is the physical position that corresponds to R = 0? What happens to the magnetic field when the radius of the coil becomes very large? What happens far away from the coil?

Explanation / Answer

(a)
Z is the distance along the axial direction.
Physical Position that Correspond to z = 0 is the center of the circular coil.
B = (uo*I*N)/2*R

(b)
R is the Raidus of the Loop,
If R = 0 i.e No Loop exists and therefore No Magnetic Field.
Bz = 0

(c)
R >> Z
Expression of Magnetic Field changes to,
B = (uo*I*N)/2*R
This is the Expression of Magnetic Field at the center of the loop.

(d)
Z >> R
B = (uo*I*N) * R^2/Z^2

AS R is very Small compared to Z,
Therefore B Is very very small approximating to zero.
B ~ 0

Related Questions

Navigate

• Browse (All)
• Browse M
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.